A control apparatus for an injection molding machine has a unit for setting data corresponding to a molding operation of the injection molding machine and for controlling the molding operation of the machine based on a setting of a setting unit. The setting unit has a register for holding numerical input data, an input/output control unit for inputting and outputting numerical value data to and from the register on the basis of an external command, a numerical value manipulating unit for incrementing and decrementing the numerical value data in the register through a manual operation, a numerical value display unit for displaying numerical value data stored in the register, and a place position shifting unit for shifting set places in the numerical value display and in the numerical value manipulating unit on the basis of the number of places in the integer part of the numerical value data.