PURPOSE: To provide an armature core and insulation coating method therefor in which low cost mass production can be realized while reducing production of out gas significantly and a high quality coil can be realized while making a motor thin easily.

CONSTITUTION: The armature core 1 is applied with an insulation coating 5 of polyimide resin substantially over the entire surface of a laminated core 4. The insulation coating 5 is applied to the armature core 1 by a method comprising a step for mounting the laminated core 4 including a plurality of core plates onto a carrier 6, a step for applying polyimide resin to the surface of the laminated core 4 mounted on the carrier 6, and a step for heat treating the laminated core 4 to cure the polyimide resin.