diff --git a/doc/lcurl.ldoc b/doc/lcurl.ldoc
index bcacd2c..151b12d 100644
--- a/doc/lcurl.ldoc
+++ b/doc/lcurl.ldoc
@@ -121,6 +121,17 @@ end
 -- @type error
 --
 do
+
+--- Get the error category.
+-- 
+-- @treturn number number of error category (curl.ERROR_XXX constants)
+-- 
+-- @usage
+-- if err:category() == curl.ERROR_EASY then
+-- -- proceed easy error
+-- end
+function category       ()end
+
 --- Get the number value of error.
 -- 
 -- @treturn number number of error (curl.E_XXX constants)
diff --git a/src/lcerror.c b/src/lcerror.c
index 2efac32..3a806e9 100644
--- a/src/lcerror.c
+++ b/src/lcerror.c
@@ -156,6 +156,12 @@ static int lcurl_err_equal(lua_State *L){
   return 1;
 }
 
+static int lcurl_err_category(lua_State *L){
+  lcurl_error_t *err = lcurl_geterror(L);
+  lua_pushinteger(L, err->tp);
+  return 1;
+}
+
 //}
 
 //{
@@ -199,6 +205,8 @@ static const struct luaL_Reg lcurl_err_methods[] = {
   {"msg",             lcurl_err_msg              },
   {"name",            lcurl_err_mnemo            },
   {"mnemo",           lcurl_err_mnemo            },
+  {"cat",             lcurl_err_category         },
+  {"category",        lcurl_err_category         },
   {"__tostring",      lcurl_err_tostring         },
   {"__eq",            lcurl_err_equal            },
 
@@ -226,6 +234,15 @@ static const lcurl_const_t lcurl_error_codes[] = {
   {NULL, 0}
 };
 
+static const lcurl_const_t lcurl_error_category[] = {
+  {"ERROR_CURL",  LCURL_ERROR_CURL},
+  {"ERROR_EASY",  LCURL_ERROR_EASY},
+  {"ERROR_MULTI", LCURL_ERROR_MULTI},
+  {"ERROR_SHARE", LCURL_ERROR_SHARE},
+  {"ERROR_FORM",  LCURL_ERROR_FORM},
+
+  {NULL, 0}
+};
 
 void lcurl_error_initlib(lua_State *L, int nup){
   if(!lutil_createmetap(L, LCURL_ERROR, lcurl_err_methods, nup))
@@ -233,4 +250,5 @@ void lcurl_error_initlib(lua_State *L, int nup){
   lua_pop(L, 1);
 
   lcurl_util_set_const(L, lcurl_error_codes);
+  lcurl_util_set_const(L, lcurl_error_category);
 }
diff --git a/src/lcurl.c b/src/lcurl.c
index 2f6ec7d..09aaa3f 100644
--- a/src/lcurl.c
+++ b/src/lcurl.c
@@ -161,12 +161,6 @@ static const lcurl_const_t lcurl_flags[] = {
 #include "lcflags.h"
 #undef FLG_ENTRY
 
-  "ERROR_CURL",  LCURL_ERROR_CURL,
-  "ERROR_EASY",  LCURL_ERROR_EASY,
-  "ERROR_MULTI", LCURL_ERROR_MULTI,
-  "ERROR_SHARE", LCURL_ERROR_SHARE,
-  "ERROR_FORM",  LCURL_ERROR_FORM,
-
   {NULL, 0}
 };
 
diff --git a/test/test_safe.lua b/test/test_safe.lua
index 4c0cc8c..b0facaf 100644
--- a/test/test_safe.lua
+++ b/test/test_safe.lua
@@ -65,4 +65,24 @@ end
 
 end
 
+local _ENV = TEST_CASE'error_object' do
+
+local curl = require "lcurl"
+
+function test()
+  local e1 = curl.error(curl.ERROR_EASY, 0) -- ok
+  assert_equal(curl.ERROR_EASY, e1:category())
+  assert_equal(curl.E_OK,       e1:no())
+  assert_equal("OK",            e1:name())
+
+  local e2 = curl.error(curl.ERROR_MULTI, 0) -- ok
+  local e3 = curl.error(curl.ERROR_MULTI, 0) -- ok
+  assert_equal(0, e1:no())
+  assert_equal(0, e2:no())
+  assert(e1 ~= e2)
+  assert(e3 == e2)
+end
+
+end
+
 if not HAS_RUNNER then lunit.run() end