Abstract: The present invention relates to an optical temperature sensor, comprising: a housing; a light-transmitting unit, installed in the housing, for emitting light transmitted through an optical fiber into an inner space of the housing; and a bimetal device, movably installed in the housing, for varying the amount of transmitted light, wherein the optical temperature sensor is capable of measuring a temperature by using the amount of light, from the light transmitted via the optical fiber, which is shielded through bending due to a change in the temperature of the bimetal device, or using the amount of light, from the transmitted light, which is reflected and received. The optical temperature sensor has a simple structure and is not particularly restricted in terms of installation space.