A portable electronic card system and a verifying method thereof are provided. The portable electronic card system includes: a portable personal electronic device, a rewritable card, and a writing device. The portable personal electronic device is used for obtaining a certificated code and a personal information from a remote controller. When a bidirectional verifying communication is performed between the remote controller and the portable electronic device to download the personal information, security code stored in the rewritable card be compared with security code stored in the portable electronic device for verifying and writing the personal information into the rewritable card, and another security code is generated to update or replace the original security code stored in the portable electronic device and the rewritable card.