A semiconductor memory includes a main PROM (10) for storing main data, an error correcting PROM (20) for storing correcting data, and an error correcting circuit (24) for correcting the main data with the correcting data. A control register (22) supplies a control signal to the error correcting circuit. Error correction by the correcting circuit is halted during the debugging of a program by an "invalid" control signal to avoid the danger of faulty data being supplied from the semiconductor memory.