An exhaust purification system of an internal combustion engine is provided with an electrochemical reactor provided in an exhaust passage of the internal combustion engine, and a voltage control device controlling a voltage supplied to the electrochemical reactor. The electrochemical reactor is provided with an ion conducting solid electrolyte layer and an anode layer and cathode layer placed on the surface of the solid electrolyte layer. The voltage control device is configured to perform short-circuit detection control detecting short-circuiting between the anode layer and the cathode layer, and energizing control applying current between the anode layer and the cathode layer so to energize the short-circuited part when short-circuiting is detected.