PURPOSE: To quickly execute the partial clear of a direct map type or set associative type buffer memory.

CONSTITUTION: This data processor is provided with a latch 6 for storing a comparing value for the partial clear of the buffer memory and control logic 8 for asserting a clear signal when a tag read out from a tag array 2 is compared with the comparing value of the latch 6 by a comparator 7 and both the values coincide with each other, and generating a hit signal and a new V flag based upon a V flag and coincident, clear and type signals. When coincidence is detected by the comparator 7, the V flag of an entry is turned from a clear queuing state to an invalid state. Consequently, the partial clear of the buffer memory can quickly be executed independently of capacity.