a defrosting apparatus including a housing defining a space for accommodating therein articles to be defrosted , a heater for heating the air within the housing , and an air circulation fan for circulating the heated air so that it flows through the space . the apparatus further includes a first temperature sensor disposed on the air outlet side of the circulation fan for sensing the temperature of the outlet air flowing out from the circulation fan to produce a first detection signal , a second temperature sensor disposed at the air inlet side of the circulation fan for detecting the temperature of the air flowing into the circulation fan to produce a second detection signal and a controller coupled to the first and second sensors for receiving the first and second detection signals , respectively , to thereby control the operation of the defrosting apparatus . the controller includes a first comparator for comparing the temperature represented by the second detection signal with a defrosting start temperature to energize the heater when the former is lower than the latter , a second comparator for comparing the first detection signal with a reference signal to selectively deenergize or energize the heater on the basis of the reference signal , and a third comparator for comparing the temperature represented by the second detection signal with a defrosting end temperature to complete the defrosting operation when the former is higher than the latter .