According to one embodiment, an information processor includes an operator and an address protector. The address protector includes a register access interface, an address table, and an access determination module. The register access interface is configured to receive address protection information from the operator. The address table is configured to store the received address protection information. The access determination module is configured to determine whether an access to an address specified by the operator is allowable based on the address protection information, and configured to output an interrupt signal to the operator when the access is unallowable.