A position detection system includes a responder configured to be carried by a user; interrogators, and a position detection unit configured to detect the user. The responder includes: a responder reception unit configured to receive interrogator identification information and floor identification information from the interrogator, a current floor identification information storage unit configured to store therein the floor identification information, and a responder transmission unit configured to determine whether to transmit the user identification information to the interrogator, when a transmission source of the received interrogator identification information is the interrogator provided in the room, and wherein the position detection unit comprises a position determination unit configured to detect that a position in the room of the floor, at which the user exists, is adjacent to the interrogator, based on the interrogator identification information and user identification information received from the interrogator.