Abstract: Provided are an electrochemical catalyst and a preparation method therefor. The preparation method for an electrochemical catalyst may comprise the steps of preparing a base metal aqueous solution containing a base metal, hydrothermally synthesizing a base structure containing an oxide of the base metal by using the base metal aqueous solution, and using a heat treatment method for the base structure in a sulfur (S)-containing reactive gas atmosphere, exchanging oxygen (O) on the surface of the base structure with sulfur (S) of the reactive gas to form a catalyst structure which has a core structure containing the oxide of the base metal and a shell structure containing a sulfide of the base metal.