To keep the life of an AC power cable long even when it is used in the water immersed charged state by heat cross-linking a resin composition blended with carbon black and an organic peroxide of specific pts.wt. respectively with a polyethylene resin to form a cross-linked polyethylene insulating layer on a conductor.

This AC power cable is provided with an inner semiconductive layer, a cross-linked polyethylene insulating layer, and an outer semiconductive layer on a conductor. A resin composition blended with carbon black of 0.1-0.8 pts.wt. and an organic peroxide of 0.1-5 pts.wt. with a polyethylene resin of 100 pts.wt. are heated and cross-linked to form the cross-linked polyethylene insulating layer in this AC power cable. Since a trace quantity of carbon black is blended in the cross-linked polyethylene layer, even when the AC power cable is used in the water immersed charged state, a water tree is suppressed without increasing the tan δ of the cross-linked polyethylene insulating layer, and its life can be kept long.