To provide a bonding structure of resin parts constituted so as to hold a bonded state and airtightness over a long period of time.

In a structure for bonding one resin part and other resin part, one resin part is constituted of a reinforced or non-reinforced resin such as polyamide (PA), polybutylene terephthalate(PBT), polyacetal (POM), polyethylene terephthalate(PET), polyphenylene sulfide(PPS) or the like and the other resin part is constituted of high density polyethylene(HDPE) and a modified polyethylene layer having good bonding properties with respect to both resin parts is used to bond both of them.