To achieve pressure adjustment based on accurate and precise detection of pressure distribution even if the pressure is concentrated; and to provide an air mat device comfortable to sleep.

The air mat device has a sensor for detecting distribution of the pressure applied to an elastic sheet by light emitting parts and light receiving parts of optical fiber uniformly distributed in the elastic sheet. An amount of a gas filling an air mat is adjusted based on the pressure distribution detected by the sensor. The sensor can be mounted in an upper part of the air mat of the air mat device.