PURPOSE: To obtain the comprehension rate of the branching direction with a single measuring operation by using a branching direction deciding means.

CONSTITUTION: An address store means 1 is prepared to store the address of a microinstruction under execution together with a microinstruction store means 2 which stores the microinstruction under execution, a branching direction deciding means 3 which output the branching direction information based on the branch type information and the branch condition selection information described in the microinstruction stored in the means 2, an information storage means 4 which stores the branching direction information given from the means 3 in response to each address outputted from the means 1, and an initialization/ read means 5 which initializes and reads the contents of the means 4. Thus it is possible to decide whether all cases are tested or not to a noted microinstruction address when the execution is shifted from plural microinstructions. Then the comprehension rate of the branching direction can be measured in a single process.