To propose a new value for a seat, a seat system which can make notification of advertising information fit for an occupant seated on the seat with a sensor included therein is provided. The seat system includes: a seat which includes a seat body, and a sensor provided in the seat body and configured to acquire information for use in identifying a physical state of an occupant seated on the seat body; a server having pieces of advertising information stored therein; and a terminal capable of acquiring the information from the sensor and communicating with the server. The terminal or the server is configured to choose, based on the information or an evaluation value based on the information, a piece of advertising information related to the information or the evaluation value from among the pieces of advertising information, and notify the occupant of the piece of advertising information.