A method for producing a catalyst comprising: a metal oxide having a bulk composition represented by the following formula ; and silica: Mo 12 Bi a Fe b X c Y d Z e O f wherein X represents at least one element selected from the group consisting of nickel, cobalt, magnesium, calcium, zinc, strontium, and barium; Y represents at least one element selected from the group consisting of cerium, chromium, lanthanum, neodymium, yttrium, praseodymium, samarium, aluminum, gallium, and indium; Z represents at least one element selected from the group consisting of potassium, rubidium, and cesium; a, b, c, d, e and f represent the atomic ratio of each element, and satisfy 0.1≤a≤3.0, 0.1≤b≤3.0, 0.1≤c≤10.0, 0.1≤d≤3.0, and 0.01≤e≤2.0, respectively, and f represents the number of oxygen atoms needed to satisfy atomic valence requirements of the other elements present therein, said method comprising: a preparation step of preparing a precursor slurry comprising molybdenum, bismuth, iron, silica, and a carboxylic acid; a drying step of spray-drying the precursor slurry and thereby obtaining dried particles; and a calcination step of calcining the dried particles, wherein the preparation step comprises: a step (I) of mixing a starting material for silica with the carboxylic acid and thereby preparing a silica-carboxylic acid mixed liquid having a pH of 6.5 or less; and a step (II) of mixing the silica-carboxylic acid mixed liquid, molybdenum, bismuth, and iron. silica: Mo 12 Bi a Fe b X c Y d Z e O f wherein X represents at least one element selected from the group consisting of nickel, cobalt, magnesium, calcium, zinc, strontium, and barium; Y represents at least one element selected from the group consisting of cerium, chromium, lanthanum, neodymium, yttrium, praseodymium, samarium, aluminum, gallium, and indium; Z represents at least one element selected from the group consisting of potassium, rubidium, and cesium; a, b, c, d, e and f represent the atomic ratio of each element, and satisfy 0.1≤a≤3.0, 0.1≤b≤3.0, 0.1≤c≤10.0, 0.1≤d≤3.0, and 0.01≤e≤2.0, respectively, and f represents the number of oxygen atoms needed to satisfy atomic valence requirements of the other elements present therein, said method comprising: a preparation step of preparing a precursor slurry comprising molybdenum, bismuth, iron, silica, and a carboxylic acid; a drying step of spray-drying the precursor slurry and thereby obtaining dried particles; and a calcination step of calcining the dried particles, wherein the preparation step comprises: a step (I) of mixing a starting material for silica with the carboxylic acid and thereby preparing a silica-carboxylic acid mixed liquid having a pH of 6.5 or less; and a step (II) of mixing the silica-carboxylic acid mixed liquid, molybdenum, bismuth, and iron. a preparation step of preparing a precursor slurry comprising molybdenum, bismuth, iron, silica, and a carboxylic acid; a drying step of spray-drying the precursor slurry and thereby obtaining dried particles; and a calcination step of calcining the dried particles, wherein the preparation step comprises: a step (I) of mixing a starting material for silica with the carboxylic acid and thereby preparing a silica-carboxylic acid mixed liquid having a pH of 6.5 or less; and a step (II) of mixing the silica-carboxylic acid mixed liquid, molybdenum, bismuth, and iron. a step (I) of mixing a starting material for silica with the carboxylic acid and thereby preparing a silica-carboxylic acid mixed liquid having a pH of 6.5 or less; and a step (II) of mixing the silica-carboxylic acid mixed liquid, molybdenum, bismuth, and iron. <EOS>