PURPOSE: To obtain the objective compound in high yield, by oxidizing methallyl alcohol with molecular oxygen in the presence of a specific catalyst containing an oxide of cobalt and/or nickel, and iron, bismuth and cobalt, as an essential component.

CONSTITUTION: Methacrolein useful as an intermediate of methacrylic acid, etc. is produced in high yield, by oxidizing methallyl alcohol with molecular oxygen in the presence of a catalyst having the composition of formula (A is Co and/or Ni; X is Li, Na, K, Rb, Cs and/or Tl; aWf are numbers of A, Fe, Bi, X, Mo and O atoms; when e=12, then a=2W15, b=0.1W10, c=0.1W10, d=0W1.0, and f is a value defined by the atomic valences of the other elements). Since the reaction product is almost free from the substance having adverse effect to a methacrolein oxidization catalyst, e.g. isobutylene, etc., it can be used as a raw material of methacrylic acid without purification.