A catalyst, includes: a carbon support that possesses functional groups including a carboxyl group; and a metal that is supported onto the carbon support, wherein the proportion of the carboxyl group to the functional groups is 10% or higher. A method for producing a catalyst includes: (i) supporting metal particles onto a carbon support; (ii) bringing the carbon support into contact with an acid solution; and (iii) calcining the carbon support after Step (ii), wherein the carbon support included in the produced catalyst possesses functional groups including a carboxyl group, and the proportion of said carboxyl group to the functional groups is 10% or higher.