Digital content trading system and method applied to mobile apparatus

A digital content trading system applied to a mobile apparatus, comprising:

• a mobile apparatus, pre-installing one or more digital contents, having a digital content playing means, a communication means, and a decryption means, wherein the mobile apparatus decrypts privilege of fully accessing the digital content as receiving a registration signal;
• a mobile communication provider providing a communication service and a payment service, wherein the mobile apparatus wirelessly connects with the mobile communication provider and thereby transmits the signal;
• a digital content provider, including a database recording digital contents, having a wireless communication means, a digital content broadcasting means, and a registration code generating means, wherein the digital content provider transmits the registration signal based on an identification of the mobile apparatus after successfully conducting the payment.