This invention provides a precise current load device. A cell includes a power supply line, a ground line, first and second voltage supply lines, a signal line, first, third and fourth control lines, first to fourth switches, a p-type TFT, a capacitance element, and a current load element. A source of the p-type TFT is connected to the power supply line, one terminal of the current load element is connected to the ground line, the first switch is connected between the signal line and a drain of the p-type TFT, the second switch is connected between the drain and the gate of the p-type TFT, the third switch is connected between the drain of the p-type TFT and the current load element, and the fourth switch is connected between the voltage supply line and the current load element.