Secondary battery

A secondary battery, comprising:

• a first electrode, a second electrode, an electrolyte, and a separator, wherein:
• the first electrode and the second electrode are overlapped together, with the separator interposed between the first electrode and the second electrode;
• the first electrode includes a belt-shaped current collector, and a mixture layer disposed on the current collector;
• the first electrode has an end part including one end in a width direction, and a main part other than the end part, the end part having an exposed portion where the current collector is exposed without the mixture layer formed on a surface of the current collector;
• the separator includes a porous substrate layer, and a protective layer configured to contain resin particles and covering the porous substrate layer;
• and
• when the separator is divided in two in the width direction, into a first region facing the main part and a second region facing the end part,
• an exposed area A1 per one resin particle exposed on a surface of the separator in the first region is larger than an exposed area A2 per one resin particle exposed on the surface of the separator in the second region.