The present invention relates to a heat exchanger applied for an IC production line or the like, wherein, on plural independent tube holding holes 20 formed on holding plates 20, ends of resin tubes are arranged, and a predetermined length range &agr; of the each resin tube is integrally fused into the each holding plate inside the tube holding holes. Each fusing portion for fusing the plural resin tubes into the holding plates has a non-contacted congestion structure wherein the resin tubes are not mutually contacted, thereby increasing reliability on connecting the fusing portion, and meanwhile, facilitating miniaturization of the heat exchanger by increasing heat-exchange efficiency and elements such as the resin tubes and the holding plates may be made of a fluororesin.