PURPOSE: To perform control with less hardware without implementing a branch to an address stored in a stack, by providing a means which change the address stored in the stack wherein the address of a control storage device is stored.

CONSTITUTION: The control storage device 1 stores plural microinstructions is connected to a microinstruction register 2 by a line 101; some of its output is inputted to a switching circuit 6 and the remainder is inputted to a decoding circuit 7. Some of the decoding output of the decoding circuit 7 is led to the switching circuit 6 through a line 106 and part of the microinstruction register 2 and a stack output 4 are switched according to the logical value of the output of the circuit 6. The remainder is inputted to a stack pointer control circuit 5 to control an increment or decrement of a stack pointer. An address stacker 4 is stored with plural return addresses from subroutines and connected to the switching circuit by a line 107. The output of the switching circuit 6 is led as the address of the control storage 1 and also led to an increment register 3 through an adding circuit 8.