Disclosed is an automatic icemaker has a rotatably supported ice making portion having first and second ice making trays arranged in a back-to-back manner, a motor for rotating the ice making portion, a first and a second temperature detecting sensors for detecting the temperature of the first and second ice making tray or the temperature of ice within a compartment of the first and second ice making tray, and a signal processor for controlling the motor to turn over the ice making portion after the temperature of the first or second ice making tray, or the temperature of ice within a compartment of the first or second ice making tray, looking upward, detected by the first temperature detecting sensor or the second temperature detecting sensor has become stabilized in the vicinity of 0° C.