To provide an insulating varnish for forming an insulation coating having adhesiveness with a conductor and softening resistance under high-load conditions, even after heating treatment, and an insulation wire using this.

The varnish includes base resin with 50 to 99 wt.% of phenoxy resin and 50 to 1 wt.% of polyester imide resin, and 0 to 50 pts.wt. of curing agent to 100 pts.wt. of the phenoxy resin. The curing agent is preferably a block isocyanate compound. It is preferable to use the insulating varnish having this composition as a primer layer.