PURPOSE: To simplify a bus circuit and to reduce a chip size by using the circuit output of the OR of a power-on one-shot signal and a data transfer gate open/ close signal as the open/close signal of a switch.

CONSTITUTION: A column address decoder group 1, serial data selector group 2, data transfer gate open/close signal generation circuit 3, power-on one-shot signal generation circuit 4, data bus group 5 for column address decoder output transfer are provided, and a signal 1 is a data transfer gate open/close signal and is turned to a high level only when transferring a column address decoder output to a serial data selector. A signal 2 is a power-on one-shot signal and is turned to a high level temporarily when a power source is turned on. Thus, since the transfer gate is operated by the power-on one-shot signal as well, the data bus directly inputting the power-on one-shot signal to the serial data selector is not required and the increase of the chip size can be suppressed.