PURPOSE: To realize a first-in first-out memory circuit into which an input data can be written in correct order.

CONSTITUTION: The first-in first-out memory circuit comprises N flip-flop circuits 3-1,..., 3-n having inputs entirely short-circuited to a serial/parallel converter 2 at the input section, and a control circuit 8 for holding the input data from a head bit flip-flop circuit 3-1 in the N flip-flop circuits 3-n according to the order of input. Even if the operation is interrupted at a moment of time when a data other than a multiple of N is written in, the serial/parallel conversion data at that moment can be stored correctly in an N-bit internal random access memory 5.