According to the present invention, an α-substituted acrylic ester monomer for a fluorinated resist is produced by direct addition of an α-substituted acrylic acid to a fluorinated alkene in the presence of a specific acid catalyst having a sulfonyl group. By the use of such a specific acid catalyst, it is possible to achieve industrial-scale production of the α-substituted acrylic ester monomer for the fluorinated resist by carrying out the target addition reaction of the fluorinated alkene and the α-substituted acrylic acid efficiently during the occurrence of side reactions such as isomerization of the alkene, generation of a diol and excessive addition of the α-substituted acrylic acid.