To provide a reliable cast insulated conductor, and its manufacturing method, with stable electric characteristics over a long period of time, without fear of leak of air left in a gap of connecting parts at casting.

The cast insulated conductor is provided with a first center conductor 20 used for an electric apparatus, a second center conductor 22 connected to the first center conductor 20, a sealing insulating layer 30 fitted at a connecting part of the first center conductor 20 with the second center conductor 22, and an insulating layer 24 integrally formed by casting around the first center conductor 20 and the second center conductor 22 where the sealing insulating layer 30 is installed.