In an apparatus, a temperature obtainer obtains, in a learning mode of the apparatus during a conductive carrier being deenergized a, value of a carrier temperature based on a physical parameter correlative with the carrier temperature and different from a carrier resistance. A resistance obtainer instantaneously energizes, in the learning mode, the conductive carrier to obtain a value of the carrier resistance during the instant energization. A calculator obtains, in a normal operation mode of the apparatus after the learning mode, a value of the carrier resistance, and calculates, in the normal operation mode, a value of the carrier temperature based on: the obtained value of the carrier resistance in the normal operation mode, and a pair of the value of the carrier temperature and the value of the carrier resistance obtained in the learning mode.