A power source control device configured to perform PWM control, in cycles having a PWM period, on a plurality of power source units (11 - 18) by outputting a respective ON/OFF instruction to each of the power source units (11 - 18), the ON/OFF instructions being PWM signals, the power source control device comprising: an acquisition unit configured to acquire an instruction that specifies a duty ratio of the PWM control, at a given cycle of a timer interrupt period within the PWM period, wherein the timer interrupt period is shorter than the PWM period and is obtained by dividing the PWM period by a predetermined number; a generation unit configured to generate operation data for the entire PWM period, the operation data determining whether to cause the individual power source units to perform an ON operation or an OFF operation in cycles within the timer interrupt period, the generation unit being configured to generate one set of operation data for each cycle of the timer interrupt period; an output unit configured to output the ON/OFF instructions corresponding to the operation data generated by the generation unit to the plurality of power source units (11 - 18) characterized in that: the output unit is a port register having a number of ports that corresponds to the number of power source units (11 - 18), the generation unit comprises: a storage unit configured to store the operation data generated by the generation unit; a transferring unit configured to transfer, out of the AutoNetworks Technologies, Ltd. et al. operation data stored in the storage unit, sets of the operation data to the output unit in respective synchronization with the cycles of the timer interrupt period; a predetermined table; and a writing unit configured to organize the operation data into sets of the operation data respectively corresponding to the cycles of the timer interrupt period and to write the sets of the operation data one after another into the predetermined table, and the power source control device is configured to store the operation data written into the predetermined table in the storage unit; and the output unit is configured to output the ON/OFF instructions in respective cycles of the timer interrupt period. an acquisition unit configured to acquire an instruction that specifies a duty ratio of the PWM control, at a given cycle of a timer interrupt period within the PWM period, wherein the timer interrupt period is shorter than the PWM period and is obtained by dividing the PWM period by a predetermined number; a generation unit configured to generate operation data for the entire PWM period, the operation data determining whether to cause the individual power source units to perform an ON operation or an OFF operation in cycles within the timer interrupt period, the generation unit being configured to generate one set of operation data for each cycle of the timer interrupt period; an output unit configured to output the ON/OFF instructions corresponding to the operation data generated by the generation unit to the plurality of power source units (11 - 18) the output unit is a port register having a number of ports that corresponds to the number of power source units (11 - 18), the generation unit comprises: a storage unit configured to store the operation data generated by the generation unit; a transferring unit configured to transfer, out of the AutoNetworks Technologies, Ltd. et al. operation data stored in the storage unit, sets of the operation data to the output unit in respective synchronization with the cycles of the timer interrupt period; a predetermined table; and a writing unit configured to organize the operation data into sets of the operation data respectively corresponding to the cycles of the timer interrupt period and to write the sets of the operation data one after another into the predetermined table, and a storage unit configured to store the operation data generated by the generation unit; a transferring unit configured to transfer, out of the AutoNetworks Technologies, Ltd. et al. operation data stored in the storage unit, sets of the operation data to the output unit in respective synchronization with the cycles of the timer interrupt period; a predetermined table; and a writing unit configured to organize the operation data into sets of the operation data respectively corresponding to the cycles of the timer interrupt period and to write the sets of the operation data one after another into the predetermined table, and the power source control device is configured to store the operation data written into the predetermined table in the storage unit; and the output unit is configured to output the ON/OFF instructions in respective cycles of the timer interrupt period.