Stator and method of assembling stator

A method of assembling a stator, comprising:

• putting insulating paper into a slot provided in a stator core, the slot including an opening in an end surface of the stator core that faces an axial direction, the opening including an expanded portion whose width is increased in a first direction, and the insulating paper being accommodated in the expanded portion with a part of the accommodated insulating paper overlapping twice or more;
• putting a part of a coil into the slot and inside the insulating paper;
• and
• bending a coil end portion of the coil that protrudes from the end surface, the first direction being a direction in which the coil end portion is bent.