diff --git a/NEWS b/NEWS
index b85aed1..798c881 100644
--- a/NEWS
+++ b/NEWS
@@ -59,6 +59,7 @@ 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#@+ and Matrix#@- .
 
 * Method
   * New methods:
diff --git a/lib/matrix.rb b/lib/matrix.rb
index ee5a716..fe76ca0 100644
--- a/lib/matrix.rb
+++ b/lib/matrix.rb
@@ -87,6 +87,7 @@ end
 # * #inv
 # * #**
 # * #+@
+# * #-@
 #
 # Matrix functions:
 # * #determinant
@@ -1045,6 +1046,10 @@ class Matrix
     self
   end
 
+  def -@
+    collect {|e| -e }
+  end
+
   #--
   # MATRIX FUNCTIONS -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
   #++
diff --git a/test/matrix/test_matrix.rb b/test/matrix/test_matrix.rb
index 13ffbb8..d6a420b 100644
--- a/test/matrix/test_matrix.rb
+++ b/test/matrix/test_matrix.rb
@@ -61,6 +61,11 @@ class TestMatrix < Test::Unit::TestCase
     assert_equal(@m1, +@m1)
   end
 
+  def test_negate
+    assert_equal(Matrix[[-1, -2, -3], [-4, -5, -6]], -@m1)
+    assert_equal(@m1, -(-@m1))
+  end
+
   def test_rank
     [
       [[0]],