An electro-optical device having high operation performance and reliability, and a manufacturing method thereof A TFT structure which is strong agains hot carrier injection is realized by disposing a Lov region 207 in an n-channel TFT 203 which forms a driver circuit. Further, Loff regions 217 to 220 and offset region are disposed in an n-channel TFT 304 which forms a pixel section, and a TFT structure of low OFF current value is realized. Further, by reducing the n-type impurity element contained in Loff regions 217 to 220 to approximately 1.times.10.sup.16 to 5.times.10.sup.18 atoms/cm.sup.3, further reduction of OFF current can be performed.