To provide an on-board power system which can easily attain higher voltage and moreover, can supply electric load with power in stable manner.

A wound battery 200 is constituted of a plurality of cells 240, in each of which a group of electrode plates, each of which is made by spirally winding an object, where a separator 222 is interposed between a positive plate 221 and a negative plate 231, are immersed in an electrolyte and are stored in a container. This wound battery 200 is provided with a low potential side external connection positive electrode terminal 261 and a high potential side external connection positive electrode terminal 266; as well as, a generator 100 for charging the wound battery 200 is constituted so that it can generate and output the voltage corresponding to the low potential side external connection positive electrode terminal 261, and the voltage corresponding to the high potential side external connection positive electrode terminal 266.