To provide a means for judging the degree of vacuum in element units and to provide an electron device having the means, in the electron device that is sealed in a pressure-reduced atmosphere in element units.

The electron device is provided with an optical system 10, a board 30 having a plurality of infrared sensor elements 20 that are sealed by a cap body for each element, a Peltier element 50, a signal-processing circuit 60, an element-driving circuit 70, a temperature detection/Peltier element-driving circuit 80, and a shade 90 for inspection. The temperature of each bolometer is measured after a fixed time has elapsed by self heat generation of the bolometer in the infrared sensor element 20 for judging the degree of vacuum in each cap body. Since a temperature-retaining state in the cap body differs depending on the degree of vacuum, the degree of vacuum in each cap body can be judged by comparing a measurement temperature with a set value.