A polymerizable composition comprising: a polyurethane resin synthesized by using a compound represented by the following formula (I) as one of starting materials; a photopolymerization or thermal polymerization initiator; and an addition-polymerizable compound having an ethylenically unsaturated bond: wherein X represents a tri- or higher valent atom; R1 and R2 each independently represent a single bond or an alkylene group optionally having a substituent, provided that R1 and R2 do not represent a single bond at a same time; A represents a straight chain linking group; and n is an integer of from 1 to 5.