Manufacturing method of secondary battery and secondary battery

A secondary battery, comprising:

• an electrode body including a terminal connecting part constituted of a plurality of stacked layers of collector foils;
• an exterior body made of a laminate film for accommodating the electrode body;
• and
• an electrode terminal to be connected with the terminal connecting part,
• wherein the electrode terminal includes a first terminal joined to a lower surface of the terminal connecting part, and partially exposed to an outside of the exterior body, and a second terminal joined to an upper surface of the terminal connecting part,
• a first welding mark including a plurality of recesses and projections is formed in at least some region in a depth direction of a lower surface of the first terminal, and a width dimension W3 of the first welding mark is longer than a width dimension W2 of the second terminal,
• a second welding mark including a plurality of recesses and projections is formed from a first end to a second end in a width direction of the second terminal in at least some region in a depth direction of an upper surface of the second terminal, and
• a height dimension HC at a central part in the width direction of the second terminal, and a height dimension HE at an end in the width direction of the second terminal satisfy a relationship of HC≥HE, wherein
• a recessed part is formed at each opposite end of the second welding mark so as to be located at an outer edge of each of the first end and the second end in the width direction of the second terminal.