A liquid discharging device includes: a discharge head mounting unit having first and second electrical terminals; a power source; a switch controlling connection between the power source and the electrical terminals; and a control unit controlling the switch; wherein a driving circuit driving a liquid discharge head is closed by attachment thereof to the mounting unit; the power source can selectively output multiple voltages; and the control unit selectively effects a state for supply of a discharge electrical power, in which electric power sufficient for a discharging actuator of the discharge head to discharge liquid is supplied thereto by controlling the switch, and a state for diagnosis, in which, wherein electric power insufficient for the discharging actuator to discharge liquid is supplied thereto by controlling the switch, and in which the voltage of at least one of the terminals is measured, and information of the state of the power source, discharging actuator, and driving circuit, is obtained.