A protocol conversion apparatus includes: a first communication unit that communicates with a power conditioner that supports a first charging protocol; a second communication unit that communicates with an electric vehicle that supports a second charging protocol; and a control unit that is a conversion unit placed between the first communication unit and the second communication unit, which receives from the first communication unit a communication signal received from the power conditioner, and upon the reception, converts the received signal to a communication signal that conforms to the second charging protocol to output the resultant signal to the second communication unit, and which receives from the second communication unit a communication signal received from the electric vehicle, and upon the reception, converts the received signal to a communication signal that conforms to the first charging protocol to output the resultant signal to the first communication unit.