There is provided an EL light-emitting device with less uneven brightness. When a drain current of a plurality of current controlling TFTs is Id, a mobility is .mu., a gate capacitance per unit area is Co, a maximum gate voltage is Vgs.sub.(max), a channel width is W, a channel length is L, an average value of a threshold voltage is Vth, a deviation from the average value of the threshold voltage is .DELTA.Vth, and a difference in emission brightness of a plurality of EL elements is within a range of .+-.n %, a semiconductor display device is characterized in that.times..times..times..times..mu..ltoreq..ltoreq..DELTA..times..times.- .DELTA..times..times..ltoreq. ##EQU00001##