To provide an insulation method and an insulation construction device of a wire connection capable of performing insulation processing of a wire connection easily and reliably.

A sleeve 103, i.e., a connection of wires 101 and 102, is surrounded by molds 2, 3. After covering the sleeve 103 with a solidifiable and viscous electrical insulator G filling a cavity 4 of a predetermined shape formed in the molds 2, 3, the viscous electrical insulator G is solidified in the molds 2, 3 and integrated with the sleeve 103. Thereafter, an insulation part G1 consisting of the solidified viscous electrical insulator G is separated from the molds 2, 3.