A belt with built-in batteries includes: a plurality of rechargeable batteries, each having a positive terminal and a negative terminal that protrude in two opposite directions; a positive reinforcing tab that electrically connects the positive terminals of the rechargeable batteries to each other; a negative reinforcing tab that electrically connects the negative terminals of the rechargeable batteries to each other; and a sheath that seals the positive and negative terminals of the rechargeable batteries and the positive and negative reinforcing tabs.