PURPOSE: To quickly cool the hollow part heated during signal readout after reading out the signal and increase drive speed by forming a penetration hole communicated with hollow part in a base and increase drive

CONSTITUTION: By using a suction/injection device, such cooling gas as air and volatile liquid such as ethyl alcohol are injected from base 1 surface through a penetration hole 10b, a groove 12 and a penetration hole 10a into the hollow part 11 formed just below an insulation film 4. By this, the heat of pyroelectric material film 8 heated during signal readout can be removed to be cooled. The gas and liquid in the hollow part 11 after removing heat from the pyroelectric material film 8 are sucked from the base 1 surface through the penetration hole 10b, the groove 12 and the penetration hole 10a and exhausted after the signal readout by using the suction/injection device. Thus, the hollow part 11 and the pyroelectric material film 8 can be cooled efficiently and quickly after the signal readout more than in the case only hollow part 11 is provided. By this, the drive speed can be increased.