A low-cost, small-size Wilkinson-type combiner that suppresses the risk of damaging an isolation resistor due to combination loss is provided. The combiner comprises first and second input terminals to which RF signals are input; an output terminal; a wiring line that combines the RF signals input to the first and second input terminals, and outputs the combined signal to the output terminal; an isolation unit provided between the first and second input terminals and formed by a first isolation resistor, a transformer, and a second isolation resistor connected in series; a detection circuit connected to a secondary coil of the transformer and configured to detect a current flowing in the secondary coil; and a determination circuit that outputs a control signal to block input of RF signals to the first and second input terminals if the current flowing in the isolation unit and detected by the detection circuit is higher than or equal to a prescribed value.