A power supply control apparatus includes a plurality of power supply units for supplying electric power to a plurality of electric circuits respectively. The power supply control apparatus receives pulse signals from the exterior. Each of the plurality of power supply units comprises a counter for counting the pulse signals. And a controller initiates to supply of the electric power to corresponding one of the electric circuits when the number of the pulse signals counted by the counter reaches the particular value which corresponds to an initiating timing of supplying electric power to corresponding one of the electric circuits.