Provided is a Michael addition product prepared from a multifunctional acryl monomer having multiple hydroxyl groups allowing introduction of acryl functional groups, as a Michael acceptor, and a Michael donor. The Michael addition product is a novel multifunctional compound having an oligomer and a photoinitiator moiety in the molecule. Since it can be cured under a standard UV curing condition without having to add a photoinitiator, it is reduced to air pollution or health problem. Therefore the superior physical properties were obtained by cured coatings without surface tackiness. In addition, its hydroxyl groups allow, through isocyanate bonding or introduction of acryl groups, 3-dimensional crosslinking and molecular and compositional design for improving expandability, friction, and reactivity and hydrophilicity for self-adhesion, hardness of cured film, or the like. Consequently, a very useful, multifunctional or water-dispersible coating composition may be prepared.