A sensor head for an optical pressure sensor according to the present invention includes: a light-emitting optical fiber for transmitting light emitted from a light source; a reflecting plate whose position relative to an end surface of the light-emitting optical fiber moves in accordance with a pressure and which reflects the light emitted from the end surface of the light-emitting optical fiber; a first optical fiber and a second optical fiber, each of which has an end surface that the light reflected by the reflecting plate enters, the first optical fiber transmitting the light thus entered to a first photodetector and the second optical fiber transmitting the light thus entered to a second photodetector; and a light-intensity variation section that changes a transmission loss in the light-emitting optical fiber in accordance with a change in humidity in the sensor head.