Power supply controller, electric vehicle and battery control unit

A voltage measurement part 200 measures voltage Vn for each of the blocks of a battery pack 7, electric current In is measured with the same timing by a current measuring circuit 201, and a counter 206 counts the number of times an effective load power Pn obtained from a product of the electric current and voltage of each block by an electric power computation part 203 exceeds permissible electric power values Pcn and Pdn calculated by a permissible electric power computation part 205, such that when the count value is equal to or higher than a preset value, a decision part 207 outputs a contactor opening request signal Copen so as to bring the contactors into an open state and protect the battery pack.