diff --git a/pykig/pykig.py b/pykig/pykig.py
--- a/pykig/pykig.py
+++ b/pykig/pykig.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 #-------------------------------python------------------------pykig.py--#
 #                                                                       #
@@ -170,9 +170,9 @@
     self.of=of
     try:
       self.outfile = open(outfilename, 'w')
-    except IOError, value:
+    except IOError as value:
 #      print >> sys.stderr, outfilename, 'unwritable'
-      print >> sys.stderr, value
+      print(value,  file=sys.stderr)
       sys.exit(2)
 #    KigOut._kigdocument=self
     KigDOP._kd=self
@@ -212,14 +212,14 @@
       self.outfile.write(" </View>\n</KigDocument>\n")
       if self.outfile != sys.stdout:
         self.outfile.close()
-    except IOError, value:
-      print >> sys.stderr, value
+    except IOError as value:
+      print(value, file=sys.stderr)
       sys.exit(2)
     try:
       if self.callkig:
         err = os.system('kig ' + self.outfilename)
-    except Exception, value:
-      print >> sys.stderr, value      
+    except Exception as value:
+      print(value, file=sys.stderr)
     if not self.of:
       os.system('rm ' + self.outfilename)
 
@@ -501,7 +501,7 @@
 
 for d in data:
   p1, p2, p3 = d
-  exec databuild(p1, p2, p3)
+  exec (databuild(p1, p2, p3))
 
 #####
 # Objects
@@ -645,7 +645,7 @@
 
 for o in objects:
   p1, p2, p3, p4 = o
-  exec objectbuild(p1, p2, p3, p4)
+  exec (objectbuild(p1, p2, p3, p4))
 
 #####
 # Properties
@@ -688,7 +688,7 @@
 
 for p in property:
   p1, p2, p3, p4 = p
-  exec propertybuild(p1, p2, p3, p4)
+  exec (propertybuild(p1, p2, p3, p4))
 
 #####
 # Start of properties definitions as Object's methods
@@ -734,16 +734,16 @@
 
 for p in methods:
   p1, p2, cl = p
-  exec methodsbuild(p1)
+  exec (methodsbuild(p1))
   for c in cl:
     setattr(c, p2, method)
 
 #####
 # Usage
 #####
 
 def usage(codexit):
-  print >> sys.stderr, """
+  print ("""
 usage: pykig.py [options...] file ...
 
 Options:
@@ -757,7 +757,7 @@
     $ pykig.py my_file.kpy
     $ pykig.py -o output_file.kig my_file.kpy
     $ ...
-"""
+""", file=sys.stderr)
   sys.exit(codexit)
 
 #####
@@ -776,36 +776,36 @@
     _opts, _args = getopt.getopt(sys.argv[1:], "hvno:",\
                                  ["help", "version", "nokig", "output="])
   except getopt.GetoptError:
-    print "GetoptError"
+    print ("GetoptError")
     usage(2)
   _callKig=True
   _of=False
   for _opt, _arg in _opts:
     if _opt in ("-h", "--help"):
       usage(0)
     if _opt in ("-v", "--version"):
-      print "Version:", version
+      print ("Version:", version)
       sys.exit(0)
     if _opt in ("-n", "--nokig"):
       _callKig=False
     elif _opt in ("-o", "--output"):
       _outfilename=_arg
       _of=True
       _callKig=False   # if there's an output file, don't call Kig
   if len(_args)==0:
-    _infilename=raw_input("Input file name: ")
+    _infilename=input("Input file name: ")
     if not _infilename:
-      print "No input file name."
+      print ("No input file name.")
       usage(2)
   elif len(_args)==1:
     _infilename=_args[0]
   else:
-    print "No input file name."
+    print ("No input file name.")
     usage(2)
   try:
     _infile = open(_infilename, 'r')
   except:
-    print >> sys.stderr, _infilename, "input file can't be read."
+    print (_infilename, "input file can't be read.", file=sys.stderr)
     sys.exit(2)
   if _of:
     if _outfilename=="-":
@@ -817,9 +817,9 @@
   kigdocument=KigDocument(_outfilename, _callKig, _of)
   kd=kigdocument
   try:
-    execfile(_infilename, globals())
+    exec(open(_infilename).read(), globals())
   except:
-    print >> sys.stderr, 'Syntax error in', _infilename
+    print ('Syntax error in', _infilename, file=sys.stderr)
     _info = sys.exc_info()    # print out the traceback
     traceback.print_exc()
     sys.exit(3)