A plurality of transistors are connected between an I2C bus operating at a first voltage level and an I2C bus operating at a second voltage level and a main control electrode of at least one transistor is connected to a first power supply terminal and a main control electrode of the other at least one transistor is connected to an intermediate level between the first voltage level and the second voltage level, whereby a withstand voltage required to a transistor of the bidirectional level shift circuit of the I2C bus can be lowered.