A battery unit (38F) comprising a plurality of batteries (3) and a connection control device (35a, 35b, 36a, 36b, 36d, 36e) which controls electrical connection relating to the battery unit (38F) are provided in a vehicle (1). The battery unit (38F) comprises two groups (S1R, S1L) of the batteries (3) disposed to have a space (G) there-between, and the connection control device (35a, 35b, 36a, 36b, 36d, 36e) is disposed in the space (G). The layout of the connection control device (35a, 35b, 36a, 36b, 36d, 36e) is thereby optimized and the length of a harness (34) can be shortened.