To obtain a temperature sensing device with simple structure and easy design by which the temperature can be measured precisely, by a constitution wherein a sensor by which infrared rays radiated from an object to be sensed are converted into an electric signal is installed internally and a sensor cap in which a sensing hole used to pass the infrared rays through is formed in the upper part is contained.

This temperature sensing device is composed of a sensor 30 by which infrared rays are converted into an electric signal. In addition, it is composed of a sensor cap 20 in which a sensing hole 22 used to pass the infrared rays through is formed in the upper part. A hollow part in which the sensor 30 is installed internally is formed at the inside of the sensor cap 20. Then, a sensing hole 22 through which the infrared rays are passed is formed in the upper part of the sensor cap 20. An opening part is formed in the lower part in such a way that the sensor cap 20 can be installed on a circuit board 36 on which the sensor 30 is installed. In the meantime, it is preferable that the center of the sensing hole 22 almost aligns with the perpendicular direction at center of a sensor window 32 in the sensor 30, and that the size D1 of the sensing hole 22 is a little larger than the size of the sensor window 32.