dl and commonly applies the difference voltage to the gate electrodes of the first and second pmos tfts mp 1 and mp 2 the first pmos tft mp 1 is turned on by the difference voltage charged in the capacitor c and applies the supply voltage vdd at the voltage supply line vddl to the el cell elc at this time a channel width of the first pmos tft mp 1 is varied depending on a voltage level of the pixel signal to control an amount of current applied from the voltage supply line vddl to the el cell elc then the el cell elc generates light corresponding to the amount of current applied via the first pmos tft mp 1 from the voltage supply line vddl meanwhile the second pmos tft mp 2 controls a current amount flowing from the voltage supply line vddl into the data line dl when a pixel signal is applied from the data line dl thereby determining an amount of current applied to the el cell elc via the first pmos tft mp 1 a channel width of the second pmos tft mp 2 which determines a current amount flowing via the first pmos tft mp 1 as mentioned above is formed to be equal to several to tens of times the channel width of the first pmos tft mp 1 for instance a channel width ratio of the first pmos tft mp 1 to the second pmos tft mp 2 may be in a range of 1 3 through 1 20 to the contrary if the channel width ratio is in a range of 3 1 through 10.