To provide a highly reliable system for entrusting a task such as searching for and finding a lost article, searching for and rescuing a lost child, and queuing for a ticket or the like.

A Web server receives reward information from a client terminal, and stores information in various DBs. A mail server transmits request information mail to an entrustee candidate terminal located in a request region on the basis of the received request information. The Web server receives answer information from the entrustee candidate terminal, and stores it in an answer information accumulation database. The mail server transmits the answer information to the client terminal when receipt of the answer information corresponding to the request information is stored. The Web server receives correct/wrong information corresponding to the answer information from the client terminal. When the correct/wrong information indicates that the answer information is correct, the Web server transmits reward information corresponding to request ID stored in the reward management database to a settlement system.