Methacrylic acid producing catalyst and a method for producing methacrylic acid using the catalyst

The present invention provides in performance, life, acrylic manufacture of the absorbent aspects during storage for a better methyl heteropolyacid catalyst. The catalyst for producing methacrylic acid, which, in MoaPbVcCudYeZfOg (formula, Y represents cesium, Z represents iron, .a ~ g represent the atomic ratio of each element 10 with respect to the Mo atom), and with respect to 10 atoms an alkali metal atom ratio of Mo atoms is a, the copper atoms of the atomic ratio of Mo is set to 10 atomic B, and the valence is C, to satisfy α = a + (B × C), 0.5≤α≤ 1.4 way of the conditions of proton replacement.