An image forming apparatus includes an image forming apparatus body and a unit. The unit is installed on the image forming apparatus body and includes a wireless tag. The image forming apparatus body includes a first power supply unit, a setting unit, a second power supply unit, a generating unit, and a communication unit. The second power supply unit generates a second value of voltage set in the setting unit. The generating unit uses the first power supply unit as a power source and generates a first signal for transmission to the wireless tag. The communication unit uses the second power supply unit as a power source, generates a second signal having amplitude in proportion to the second value set in the setting unit based on the first signal, and transmits the second signal to the wireless tag by wireless.