diff --git a/README.md b/README.md
index b82e442..2431e07 100644
--- a/README.md
+++ b/README.md
@@ -96,6 +96,7 @@ You set the validation rules following the "validate:" tag according to the rule
| min | Check whether value is greater than or equal to the specified value
e.g. `validate:"min=1"` |
| max | Check whether value is less than or equal to the specified value
e.g. `validate:"max=100"` |
| len | Check whether the length of the value is equal to the specified value
e.g. `validate:"len=10"` |
+| oneof | Check whether value is included in the specified values
e.g. `validate:"oneof=male female prefer_not_to"` |
## License
[MIT License](./LICENSE)