A service system for offering information of invitation of public contribution and/or prize contest by using a cellular phone, a personal digital assistant, and a computer terminal machine, characterized in that a user can be permitted to easily participate in the system according to the invention, is individually provided with proper information of invitation of public contribution and/or prize contest correctly, and can apply for the information, by on-line registering basic information of the user through a cellular phone, a personal digital assistant, or a computer terminal machine connectable to the Internet, by carrying out a referring process on-line by using the basic information, and by permitting an access to a plurality of information of invitation of public contribution and/or prize contest on the Internet.