According to an aspect, a semiconductor device and an IO-cell include a plurality of first power supply lines and a plurality of second power supply lines alternately arranged in a first direction, the first and second power supply lines each being supplied with electric power in which the voltage of the electric power supplied to the first power supply is different from that supplied to the second power supply, and a third power supply line formed in a wiring layer different from a wiring layer in which the first and second power supply lines are arranged, the third power supply line being connected to adjacent first power supply lines among the plurality of first power supply lines through a via, in which all of the first, second and third power supply lines are formed so as to extend in a second direction perpendicular to the first direction.