A load testing apparatus includes: a resistor unit that has a resistor group including relays and resistors and is connected to a power source to be tested to perform a load test; a selection switch that is used to select whether to supply power from the power source to be tested to the resistor group; an electrical signal detection unit that detects at least one of a voltage applied to the resistor unit and a current flowing through the resistor unit; and a control unit. The relay operates in response to an on/off state of the selection switch to control power supply from the power source to be tested to the resistor group including the relay. The control unit performs determination on whether the relay normally operates based on detection information including a time-series change of at least one of the voltage and the current when the selection switch is operated, which is information from the electrical signal detection unit, and performs off control to stop power supply from the power source to be tested to the resistor unit.