PURPOSE: To reduce the wiring area of a serial/parallel conversion circuit consisting of an integrated circuit by employing a signal wire serving also as a data signal wire for serial data input and a control signal wire for control signal representing the start and the end of a serial data for an input signal wire to the serial/parallel conversion circuit.

CONSTITUTION: Circuit sections A, C detecting a serial data string and controlling it, and a circuit section B converting the serial data into a parallel data are provided on the title serial/parallel converter. Moreover, the converter consists of an input signal wire 1 for a serial data and a control signal representing the start and end of the serial data, an inverter 2, a 3-input NOR circuit 3, DFFs 4-9, NMOSes 10-25, parallel data output signal wires 26-28, control wires 29-32 and a clock wire 33. The signal wire 1 serving also as the data signal wire for serial data input and the control signal representing the start and end of the serial data is enough for the input signal wire to the serial/parallel conversion circuit in such a manner and the number of the required input signal wires is halved to minimize the wiring area on the integrated circuit.