diff --git a/lib/chainer/dataset/convert.rb b/lib/chainer/dataset/convert.rb
index 7c07611..5a5b800 100644
--- a/lib/chainer/dataset/convert.rb
+++ b/lib/chainer/dataset/convert.rb
@@ -29,31 +29,51 @@ def self.concat_examples(batch, device: nil, padding: nil)
 
       def self.concat_arrays(arrays, padding)
         unless arrays[0].kind_of?(Numo::NArray)
+          # [1, 2, 3, 4] => Numo::Int32[1, 2, 3, 4]
           arrays = Numo::NArray.cast(arrays)
+          if padding
+            return concat_arrays_with_padding(arrays, padding)
+          end
+          return arrays
         end
 
         if padding
           return concat_arrays_with_padding(arrays, padding)
         end
 
+        # [Numo::SFloat[1, 2], Numo::SFloat[3, 4]]
+        #  => Numo::SFloat#shape=[2,2]
+        # [[1, 2], [3, 4]]
         a = arrays.map{|arr| arr[:-, false]}
         a[0].concatenate(*a[1..-1])
       end
 
       def self.concat_arrays_with_padding(arrays, padding)
-        shape = Numo::Int32.[](arrays[0].shape)
-        arrays[1...arrays.len].each do |array|
-          if Numo::Bit.[](shape != array.shape).any?
-            # TODO: numpy maximum
+        if arrays[0].is_a? Numo::NArray
+          shape = Numo::Int32.cast(arrays[0].shape)
+          arrays[1..-1].each do |array|
+            if Numo::Bit.[](shape != array.shape).any?
+              shape = Numo::Int32.maximum(shape, array.shape)
+            end
           end
+        else # Integer
+          shape = []
+        end
+
+        shape = shape.insert(0, arrays.size).to_a
+        if arrays[0].is_a? Numo::NArray
+          result = arrays[0].class.new(shape).fill(padding)
+        else # Integer
+          result = Numo::Int32.new(shape).fill(padding)
         end
 
-        shape = [shape.insert(0, arrays.size)]
-        result = arrays[0].dtype.[](*shape).full(padding)
         arrays.size.times do |i|
           src = arrays[i]
-          slices = src.shape.map { |s| [s] }
-          result[[i] + slices] = src
+          if src.is_a? Numo::NArray
+            result[i, 0...src.shape[0], 0...src.shape[1]] = src
+          else # Integer
+            result[i] = src
+          end
         end
 
         result
diff --git a/test/dataset/convert_test.rb b/test/dataset/convert_test.rb
index c165a54..4aaadae 100644
--- a/test/dataset/convert_test.rb
+++ b/test/dataset/convert_test.rb
@@ -35,7 +35,7 @@ def get_tuple_arrays_to_concat(xumo)
   def check_concat_tuples(tuples, device: nil)
     arrays = Chainer::Dataset::Convert.method(:concat_examples).call(tuples, device: device)
     assert_equal(tuples[0].size, arrays.size)
-    for i in arrays.size.times
+    arrays.size.times do |i|
       shape = [tuples.size] + tuples[0][i].shape
       assert_equal(shape, arrays[i].shape)
       check_device(arrays[i], device)
@@ -50,3 +50,99 @@ def test_concat_tuples_cpu()
     check_concat_tuples(tuples)
   end
 end
+
+class TestConcatExamplesWithPadding < Test::Unit::TestCase
+  def check_concat_arrays_padding(xumo)
+    arrays = [xumo::DFloat.new(3, 4).rand(), xumo::DFloat.new(2, 5).rand(), xumo::DFloat.new(4, 3).rand()]
+    array = Chainer::Dataset::Convert.method(:concat_examples).call(arrays, padding: 0)
+
+    assert_equal([3, 4, 5], array.shape)
+    assert_equal(arrays[0].class, array.class)
+    arrays = arrays.map{|a| array.class.cast(a)}
+    assert_true array[0, 0...3, 0...4].nearly_eq(arrays[0]).all?
+    assert_true array[0, 3..-1, 0..-1].nearly_eq(0).all?
+    assert_true array[0, 0..-1, 4..-1].nearly_eq(0).all?
+    assert_true array[1, 0...2, 0...5].nearly_eq(arrays[1]).all?
+    assert_true array[1, 2..-1, 0..-1].nearly_eq(0).all?
+    assert_true array[2, 0...4, 0...3].nearly_eq(arrays[2]).all?
+    assert_true array[2, 0..-1, 3..-1].nearly_eq(0).all?
+  end
+
+  def test_concat_arrays_padding_cpu()
+    check_concat_arrays_padding(Numo)
+  end
+
+  def check_concat_tuples_padding(xumo)
+    tuples = [[xumo::DFloat.new(3, 4).rand(), xumo::DFloat.new(2, 5).rand()],
+              [xumo::DFloat.new(4, 4).rand(), xumo::DFloat.new(3, 4).rand()],
+              [xumo::DFloat.new(2, 5).rand(), xumo::DFloat.new(2, 6).rand()]]
+    arrays = Chainer::Dataset::Convert.method(:concat_examples).call(tuples, padding: 0)
+
+    assert_equal(2, arrays.size)
+    assert_equal([3, 4, 5], arrays[0].shape)
+    assert_equal([3, 3, 6], arrays[1].shape)
+    assert_equal(tuples[0][0].class, arrays[0].class)
+    assert_equal(tuples[0][1].class, arrays[1].class)
+    tuples.size.times do |i|
+      tuples[i] = [tuples[i][0], tuples[i][1]]
+    end
+
+    arrays = arrays.to_a
+    assert_true arrays[0][0, 0...3, 0...4].nearly_eq(tuples[0][0]).all?
+    assert_true arrays[0][0, 3..-1, 0..-1].nearly_eq(0).all?
+    assert_true arrays[0][0, 0..-1, 4..-1].nearly_eq(0).all?
+    assert_true arrays[0][1, 0...4, 0...4].nearly_eq(tuples[1][0]).all?
+    assert_true arrays[0][1, 0..-1, 4..-1].nearly_eq(0).all?
+    assert_true arrays[0][2, 0...2, 0...5].nearly_eq(tuples[2][0]).all?
+    assert_true arrays[0][2, 2..-1, 0..-1].nearly_eq(0).all?
+    assert_true arrays[1][0, 0...2, 0...5].nearly_eq(tuples[0][1]).all?
+    assert_true arrays[1][0, 2..-1, 0..-1].nearly_eq(0).all?
+    assert_true arrays[1][0, 0..-1, 5..-1].nearly_eq(0).all?
+    assert_true arrays[1][1, 0...3, 0...4].nearly_eq(tuples[1][1]).all?
+    #assert_true arrays[1][1, 3..-1, 0..-1].nearly_eq(0).all? # range error
+    assert_true arrays[1][1, 0..-1, 4..-1].nearly_eq(0).all?
+    assert_true arrays[1][2, 0...2, 0...6].nearly_eq(tuples[2][1]).all?
+    assert_true arrays[1][2, 2..-1, 0..-1].nearly_eq(0).all?
+  end
+
+  def test_concat_tuples_padding_cpu()
+    check_concat_tuples_padding(Numo)
+  end
+end
+
+class TestConcatExamplesWithBuiltInTypes < Test::Unit::TestCase
+  data = {
+    'test1' => {padding: nil},
+    'test2' => {padding: 0}}
+
+  @@int_arrays = [1, 2, 3]
+  @@float_arrays = [1.0, 2.0, 3.0]
+
+  def check_device(array, device)
+    if device && device >= 0
+      # T.B.I (GPU Check)
+    else
+      assert_true array.is_a?(Numo::NArray)
+    end
+  end
+
+  def check_concat_arrays(arrays, device:, expected_type:)
+    array = Chainer::Dataset::Convert.method(:concat_examples).call(arrays, device: device, padding: @padding)
+    assert_equal([arrays.size], array.shape)
+    check_device(array, device)
+
+    array.to_a.zip(arrays.to_a).each do |x, y|
+      assert_true Numo::NArray.cast(y).nearly_eq(Numo::NArray.cast(x)).all?
+    end
+  end
+
+  data(data)
+  def test_concat_arrays_cpu(data)
+    @padding = data[:padding]
+
+    [-1, nil].each do |device|
+      check_concat_arrays(@@int_arrays, device: device, expected_type: Numo::Int64)
+      check_concat_arrays(@@float_arrays, device: device, expected_type: Numo::DFloat)
+    end
+  end
+end