diff --git a/NEWS b/NEWS
index 6d54696..d80696f 100644
--- a/NEWS
+++ b/NEWS
@@ -59,6 +59,8 @@ with all sufficient information, see the ChangeLog file.
       by deleting the specified row and column.
     * Matrix#cofactor(row, column) returns the (row, column) cofactor
       which is obtained by multiplying the first minor by (-1)**(row + column).
+    * Matrix#laplace_expansion(num, row_or_column) returns the laplace_expansion
+      along +num+ -th +row_or_column+.
     * Matrix#@+ and Matrix#@- .
 
 * Vector
diff --git a/lib/matrix.rb b/lib/matrix.rb
index 0bc7b7c..17900dd 100644
--- a/lib/matrix.rb
+++ b/lib/matrix.rb
@@ -61,6 +61,9 @@ end
 # * #minor(*param)
 # * #first_minor(row, column)
 # * #cofactor(row, column)
+# * #laplace_expansion(num, row_or_column)
+# * #cofactor_expansion(num, row_or_column)
+# * #cofact_exp(num, row_or_column)
 #
 # Properties of a matrix:
 # * #diagonal?
@@ -639,6 +642,31 @@ class Matrix
     det_of_minor * (-1) ** (row + column)
   end
 
+  #
+  # Returns the laplace_expansion along +num+ -th +row_or_column+
+  #
+  #    Matrix[[Vector[1, 0], Vector[0, 1]], [2, 3]].laplace_expansion(0, :row)
+  #     => Vector[3, -2]
+  #
+  #    Matrix[[7,6], [3,9]].laplace_expansion(1, :column)
+  #     => 45
+  #
+  def laplace_expansion(num, row_or_column)
+    Matrix.Raise ErrDimensionMismatch unless square?
+    raise RuntimeError, "laplace_expansion of empty matrix is not defined" if empty?
+    raise ArgumentError, "#{row_or_column} should be :row or :column" unless %i(row column).include?(row_or_column)
+    unless 0 <= num && num < row_count
+      raise ArgumentError, "invalid num (#{num.inspect} for 0..#{row_count - 1})"
+    end
+
+    send(row_or_column, num).map.with_index { |e, k|
+      e * cofactor(*(row_or_column == :row ? [num, k] : [k,num]))
+    }.inject(:+)
+  end
+  alias_method :cofactor_expansion, :laplace_expansion
+  alias_method :cofact_exp, :laplace_expansion
+
+
   #--
   # TESTING -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
   #++
diff --git a/test/matrix/test_matrix.rb b/test/matrix/test_matrix.rb
index d6a420b..779a1ec 100644
--- a/test/matrix/test_matrix.rb
+++ b/test/matrix/test_matrix.rb
@@ -283,6 +283,21 @@ class TestMatrix < Test::Unit::TestCase
     assert_raise(ExceptionForMatrix::ErrDimensionMismatch) { Matrix[[2,0,1],[0,-2,2]].cofactor(0, 0) }
   end
 
+  def test_laplace_expansion
+    assert_equal(1, Matrix[[1]].laplace_expansion(0, :row))
+    assert_equal(45, Matrix[[7,6], [3,9]].laplace_expansion(1, :row))
+    assert_equal(0, Matrix[[0,0],[0,0]].laplace_expansion(0, :column))
+    assert_equal(-7, Matrix[[0,0,1],[0,7,6],[1,3,9]].laplace_expansion(2, :column))
+
+    assert_equal(Vector[3, -2], Matrix[[Vector[1, 0], Vector[0, 1]], [2, 3]].laplace_expansion(0, :row))
+
+    assert_raise(ExceptionForMatrix::ErrDimensionMismatch) { @m1.laplace_expansion(1, :row) }
+    assert_raise(ArgumentError) { Matrix[[7,6], [3,9]].laplace_expansion(2, :row) }
+    assert_raise(ArgumentError) { Matrix[[0,0,1],[0,7,6],[1,3,9]].laplace_expansion(-1, :column) }
+    assert_raise(ArgumentError) { Matrix[[7,6], [3,9]].laplace_expansion(1, :foo) }
+    assert_raise(RuntimeError) { Matrix.empty(0, 0).laplace_expansion(0, :row) }
+  end
+
   def test_regular?
     assert(Matrix[[1, 0], [0, 1]].regular?)
     assert(Matrix[[1, 0, 0], [0, 1, 0], [0, 0, 1]].regular?)