To provide a seat allocation system capable of efficiently allocating a plurality of personnel on seats and allowing participants to comfortably use without feeling congestion in an event held on a computer system.

This seat allocation system comprises an accepting means having a server for providing an event service held on the computer system and participant terminals communicably connected to the server and determining the entry or exit of a participant when the server receives a connection from the participant terminal, a table having a specified number of seats for participants, and a table increasing and decreasing means for newly adding tables on which the participants are not yet allocated when determining that the overall number of participants exceeds a specified ratio to the total number of seats when the accepting means determines the entry of the participants. When the accepting means determines the entry of the participants, if the table increasing and decreasing means determines that the total number of the participants exceeds 60% of the total number of seats, it is desirable to newly add tables on which the participants are not yet allocated.