In a secondary battery charging method, constant current charging is performed until a first predetermined voltage V0 is attained, constant voltage charging is then performed at the first predetermined voltage V0, the first constant voltage charging is completed when a charge current becomes (In−ΔIn) from In, and then n is incremented by one; and constant voltage charging is performed at a voltage Vn=Vn-1+ΔVn, a step of completing the n-th constant voltage charging when the charge current becomes (In−ΔIn) from In is repeated by incrementing n by one, and the N-th constant voltage charging in which a value of the voltage Vn reaches a second predetermined voltage VN (>V0) is completed to terminate the constant voltage charging.