It is an object of the present invention to provide (1) a copolymer for a cured product that is satisfactory in properties, such as adhesion properties, as a chip stacking adhesive or the like. The present invention is a copolymer comprising repeating units represented by formula (I), formula (II), and formula (III), (wherein R1, R2, and R3 each independently represent a hydrogen atom or a methyl group, R4 represents an alkyl group or a cycloalkyl group, R5 represents a hydrogen atom or a C1 to C6 alkyl group, m, n, and k represent a molar ratio of the respective repeating units, m represents a positive number of 0 or more and less than 1, n and k each independently represent a positive number, and satisfy a relation of m+n+k=1), and having a weight-average molecular weight in the range of 50,000 to 200,000.