Provided are a self-crosslinking polyhydroxy polyurethane resin derived from a reaction of a 5-membered cyclic carbonate compound and an amine compound and having masked isocyanate groups in its structure; a process for producing the resin; an imitation leather composed of a base fabric and a resin composition composed of the resin as its principal component and impregnated in or laminated on the base fabric; as kin material made of a thermoplastic polyolefin resin, said skin material including a thermoplastic polyolefin resin sheet and a top coat layer formed directly or via a primer layer on the sheet, wherein the top coat layer has been formed with a resin composition composed of the resin as its principal component; and a weather strip material composed, as its principal components, of the resin and a specific diorganopolysiloxane and/or a silicone oil.