A load control system includes a switch, a controller, an additional functioning unit, a power source, and an adjuster. The controller is configured to switch the switch between a conduction state and a non-conduction state. The switch is electrically connected in series to a load with respect to an alternating-current power source. The additional functioning unit is configured to perform a process different from switching operation of the switch. The power source receives electric power supplied from the alternating-current power source to generate electric power to be supplied to the controller and the additional functioning unit. The adjuster adjusts a supply time period during which the power source is supplied with electric power from the alternating-current power source in a maximum load state of a state where the additional functioning unit normally operates, electric power consumption by the additional functioning unit being maximum in the maximum load state.