A microprogram control system has first and second microprogram control units and first and second arithmetic circuits corresponding to the first and second microprogram control units, respectively. The first unit has a first control memory holding microinstructions for controlling the first arithmetic circuit and a first condition register for storing status information given as a branch condition from the first arithmetic circuit. The second unit is made up of corresponding structure. In response to a start microinstruction read out from the first control memory, the first unit stores a start command and a start address in the start microinstruction into a command register and a start address register therein, respectively, and sends the start command, the start address and the status information to the second control unit. In response to the start command, the second unit stores the status information given from the first condition register into its condition register and reads out a microinstruction from its control memory based on the start address given from the start address register.