A battery unit in one aspect of an embodiment of the present disclosure includes a plurality of cell assemblies, a positive electrode connection terminal, a negative electrode connection terminal, a plurality of switch sections, a control section, and a simultaneous on-suppression section. When an on-command signal is output from the control section to at least two of the plurality of the switch sections, the simultaneous on-suppression section performs one of enabling the on-command signal to one of the at least two switch sections and disabling the on-command signal to all of the at least two switch sections, so as to suppress the at least two switch sections from being turned on at the same time.