PURPOSE: To provide a thin-film transistor with a high packing density of CMOSFETs.

CONSTITUTION: It is known that no problem arises with a p-type drain in an n-channel transistor (or with an n-type drain in a p-channel transistor) for an inverter. Therefore, a common drain 25 of p-type (or n-type) is provided for p-channel and n-channel transistors. Specifically, one semiconductor layer 22 in a CMOSFET comprises the source region 23 of p-type for a p-channel transistor, the channel region 24 for the p-channel transistor, the common drain region 25 of p-type, the channel region 26 for an n-channel transistor, and the source region 27 of n-type for the n-channel transistor.