An image forming device includes a liquid discharge head including piezoelectric elements; a drive waveform generating unit that outputs a drive waveform; a selection unit that applies the drive waveform to the piezoelectric elements; a resonant frequency adjusting circuit that is connected in parallel with the piezoelectric elements; a switch unit that switches the resonant frequency adjusting circuit; and a switching control unit that causes the switch unit to switch in accordance with a first number of simultaneously driven piezoelectric elements. When the first number of the simultaneously driven piezoelectric elements is greater than a predetermined number, the switching control unit connects the resonant frequency adjusting circuit, so that a resonant frequency of a closed loop becomes lower than a resonant frequency of the closed loop when the first number of the simultaneously driven piezoelectric elements is less than the predetermined number.