[Object]The invention provides catalysts that are not corroded in acidic electrolytes or at high potential and have excellent durability and high oxygen reducing ability.[Solution]A catalyst of the invention includes a metal oxycarbonitride that contains titanium and at least one metal (hereinafter, also referred to as “metal M” or simply “M”) selected from silver, calcium, strontium, yttrium, ruthenium, lanthanum, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium.