Provided is a method of preparing an intermetallic catalyst. The method includes form core-shell particles including a transition metal oxide coating layer by irradiating ultrasonic waves to a precursor mixture solution including a noble metal precursor, a transition metal precursor, and a carrier to; forming intermetallic particles including a transition metal oxide coating layer by annealing the core-shell particles; and removing the transition metal oxide coating layer from the intermetallic particles.