A route switching circuit includes: a pair of normal detection routes that output voltages of a positive side connection point and a negative side connection point, which are different from each other, in multiple batteries for constituting an assembled battery; and a pair of diagnosis detection routes that output the voltages of the positive side connection point and the negative side connection point, and confirm a connection state of the normal detection routes by using the normal detection routes, which output at least one of a voltage of a positive side battery connected to a positive side from the positive side connection point and a voltage of a negative side battery connected to a negative side from the negative side connection point.