Resin composition and electric insulating sheet

An electric insulating sheet comprising:

• a polyester fiber non-woven fabric;
• and
• a resin film laminated onto the polyester fiber non-woven fabric, wherein
• the polyester fiber non-woven fabric and the resin film are thermally adhered to each other,
• the resin film has at least a surface that is thermally adhered to the polyester fiber non-woven fabric and is formed by a resin composition containing a polyether sulfone resin,
• the resin composition contains the polyether sulfone resin as a main component of its resin components and one or two or more types of resins other than the polyether sulfone resin as accessory components thereof,
• the accessory components include at least a phenoxy resin, and
• when the accessory components have a melt viscosity at 300° C. of η0 (Pa·s), and the polyether sulfone resin has a melt viscosity at 300° C. of η1 (Pa·s), the resin composition satisfies Relational expression (1) below:
• η0≥(η1·100) (1).