Insulating sheet, stator provided with same, and motor

This insulating sheet to be attached to a stator core of a motor is a sheet formed into the shape of the letter H in plan view by forming an inwardly facing notch in each of two opposing first sides. Each notch has a first corner section and a second corner section. The first corner section is formed at the intersection of a third side and a fourth side. The third side is parallel to the first side and is positioned inward of the first side. The fourth side is inclined at a first angle with respect to the third side. The first corner section has a fifth side inclined at a second angle of less than 90 degrees with respect to the third side in plan view.