A semiconductor circuit includes a parity bit adding circuit configured to add a parity bit to a data to be read by a CPU; a register configured to hold the data with the parity bit; and a parity check circuit configured to execute a parity check of said data with said parity bit held in said register, and to issue a parity error interrupt when a parity error is detected. A parity bit inverting circuit inverts said parity bit held in said register in response to completion of said parity check.