INTRAVITAL PRESSURE MEASUREMENT DEVICE

An in vivo pressure measurement device includes, for example: a light source that outputs test light; an optical fiber, to which the test light is input, at least partially including a sensor optical fiber that transmits the test light with a loss of 0.3 dB/m or more; and a light receiving unit that receives the test light transmitted through the sensor optical fiber, and measures pressure in a living body acting on the sensor optical fiber based on intensity of the test light received at the light receiving unit. The pressure in the living body may be pressure of a fluid in the living body. The sensor optical fiber may be a plastic fiber. The sensor optical fiber may have a curved part. The sensor optical fiber may be capable of being inserted into the living body.