The present invention relates to a compressor, an evaporator, a blowing fan, and a defrost control of the refrigerator unit provided with a defrosting heater for defrosting and heating the evaporator and a control method. The defrosting controlling device, sealed casing portion to form a closed space and, is accommodated in the closed casing the open casing part to form a the enclosed detection unit having a closed detection sensor for detecting the surface temperature of the evaporator, an open space and the opening is accommodated in the casing and the open detector having an open detection sensor for detecting the surface temperature of the evaporator, the compressor and the blower fan is down when the closed-detecting sensor with a respective detected sealing temperature detected by the opening detection sensor of by comparing the value and opening the detected temperature value to obtain a compensation value so as to be mutually equal, the defrosting operation when the sealing detected temperature value and opening the detected temperature value of one of the compressor and the evaporator operate compensation to the compensated value is mutually equal to It has a control unit that controls to run. As a result, written by compensating for the inherent error detection of the closure detecting sensor and the opening sensor can perform the accurate defrost operation.