1. A sensing sensor that senses a substance to be sensed based on a change of an oscillation frequency of the piezoelectric resonator, wherein the substance to be sensed which is a gas is attached to the piezoelectric resonator, and the substance to be sensed is detached by changing a temperature of the piezoelectric resonator, the sensing sensor comprising:an oscillator circuit, configured to oscillate the piezoelectric resonator;
a base, including a base main body and a lid portion at one side of the base,
wherein the base main body is provided with a depressed portion for housing the oscillator circuit, and the lid portion is for covering the depressed portion,
the base is configured to support the piezoelectric resonator at another side of the base and take the oscillation frequency to an outside of the sensing sensor;
a connection portion, being disposed at the one side of the base and connected to a cooling mechanism for cooling the base from the one side of the base; and
a temperature changing unit, being interposed between the piezoelectric resonator and the base, so as to cool and heat the piezoelectric resonator and transfer a heat radiated for cooling the piezoelectric resonator from the another side of the base to the one side of the base;
wherein the depressed portion is configured to house a circuit board including the oscillator circuit, and
a heat insulating portion for insulating heat between the base and the circuit board is disposed at one side and at another side of the circuit board.