A data processor includes an access target with the address assigned to a memory space, an access subject that gains access to the access target while specifying address, identifier, and access type, and a memory protection resource including an associative memory to perform an access control. The memory protection resource includes a plurality of entries, each including a region setting unit, an identifier determination information unit, and an attribute setting unit. When the address specified by the access subject at the access is included in the region set in the region setting unit in the entry, the identifier agrees with at least one of the identifiers specified according to the identifier determination information, and the specified access type agrees with the access type set in the attribute setting unit, the memory protection resource permits the access.