An offset voltage generating circuit sets an offset voltage through binary search based on a voltage value of the initial voltage, and a voltage controlling circuit generates an output voltage which is a predetermined gradation voltage added with the offset voltage, and applies a voltage based on the output voltage to a control terminal of a drive transistor. A current comparison circuit applies a supply voltage from a power supply to the other end of current path of the drive transistor. The current comparison circuit compares the current value of a reference current corresponding to the gradation voltage with a current value of the current flowing in the current path of the drive transistor at this time. The offset voltage generating circuit acquires a specific offset voltage corresponding to variation of the characteristic of the drive transistor based on a result of comparison performed by the current comparison circuit.