Disclosed herein is a semiconductor device that includes an access control circuit generating an internal command based on a verification result signal and an external command. The external command indicates at least one of a first command that enables the access control circuit to access a first circuit and a second command that enables the access control circuit not to access the first circuit or enables the access control circuit to maintain a current state of the first circuit. The access control circuit, when the verification result signal indicates a first logic level, generates the internal command based on the external command. The access control circuit, when the verification result signal indicates a second logic level, generates the internal command that corresponds to a second command even if the external command indicates a first command.