Method for producing methacrolein and methacrylic acid

Provided is a method for producing methacrolein and methacrylic acid, whereby it becomes possible to improve the yields of methacrolein and methacrylic acid. A method for producing methacrolein and methacrylic acid by carrying out the gas-phase catalytic oxidation of at least one raw material selected from the group consisting of isobutylene, TBA and MTBE with molecular oxygen in the presence of a catalyst comprising molybdenum, bismuth and iron using a fixed bed reactor, wherein the reaction starts at a temperature lower than a reaction temperature TA (DEG C), the reaction temperature is so controlled that the reaction rate of the raw material can become constant while rising the reaction temperature, and the reaction is terminated at a temperature higher than TA (DEG C) in which TA (DEG C) represents the boundary temperature of the activation energy of the oxidation reaction, and wherein the ratio of A to B (i.e., A/B) is 0.05 to 0.18 in which A (DEG C/hr) represents the average value of the temperature-rising rates employed until the reaction temperature reaches TA, and B (DEG C/hr) represents the average value of the temperature-rising rates employed at reaction temperatures higher than TA.