A system and method for providing e-mail address information using a mobile phone number are provided. The system includes an e-mail address information providing module that stores e-mail address mapping information for variably mapping e-mail address information including one or more e-mail addresses of each of members, who are registered in an e-mail address information providing service that provides specified e-mail address information to be mapped to a mobile phone number, to a mobile phone number of each member, recognizes a member corresponding to a mobile phone number which is received via a communication network with a request for e-mail address information, and acquires and provides specified e-mail address information to be mapped to the received mobile phone number based on the member's e-mail address mapping information; and an e-mail address converting module that converts the mobile phone number into the specified e-mail address information.