The purpose of the present invention is to provide an unsaturated group-containing ester compound which is economical, is of a good curing type, and can be used as the
raw material of a curable composition obtained from a
transesterification reaction, and to provide a
polymer using said compound as the
raw material, a thermosetting resin composition, and a curable composition. This unsaturated group-containing ester compound is characterized by having the
chemical structure represented by general formula (1). n1: 1-10.(In the expression, R1, R2 and R3 are the same or different, and represent ahydrogen, an
alkyl group, a carboxyl group, an
alkyl ester group or a structure represented by R4-[COOR5]. R4 is an aliphatic, alicyclic or aromatic alkylene group with 50 or fewer atoms in the mainchain, optionally having in the main chain one or more functional groups selected from an ester group, an
ether group, an
amide group and urethane, and optionally having a sidechain. R5 is an
alkyl group with 50 or fewer carbons. In the compound represented in general formula (1), the R4-[COOR5] group is optionally the
lactone structure of general expression (1-1).) Rx is an alkylene group of 2-10carbons optionally having a
branch chain.