A master communication circuit communicatively connected to a slave communication circuit, comprises a timer circuit that can detect a first time; a first output circuit that outputs a first output signal of one logical level for starting a detecting operation of the first time in the timer circuit, when a value transmitted to the slave communication circuit is one logical level, and for starting a detecting operation of a second time longer than the first time in the slave communication circuit; and a second output circuit that outputs a second output signal of the other logical level when the timer circuit detects the first time, wherein if a value of one logical level is transmitted to the slave communication circuit, the value of one logical level is transmitted to the slave communication circuit by not detecting the second time with the slave communication circuit, detecting the first time with the timer circuit, and outputting the second output signal with the second output circuit, and wherein if a value of the other logical level is transmitted to the slave communication circuit, the value of the other logical level is transmitted to the slave communication circuit by not detecting the first time with the timer circuit and detecting the second time with the slave communication circuit.