Mounting structure for trunk device for saddle type vehicle

A mounting structure for a trunk device for a saddle type vehicle includes: a carrier (12) provided on a saddle type vehicle (10); a trunk device (20) detachably mounted to the carrier (12); front and rear locking sections (31, 41) projecting towards the carrier (12) from a mounting surface (21) of the trunk device (20); and an engaging hook (51) which operates according to an operator's operation and which engages with the carrier (12) to fix the trunk device (20) to the carrier (12). The front locking section (31) and the rear locking section (41) are composed of a front locking hook (31) and a rear locking hook (41) which are bent in the same direction (forward or rearward). The engaging hook (51) is bent in the direction opposite to the bending direction of both the locking hooks (31, 41). At the time of a fixing operation by the operator, the engaging hook (51) is moved in the direction opposite to the bending direction of both the locking hooks (31, 41), to engage with the carrier (12). This arrangement can reduce the rigidity required of the trunk, and render the trunk smaller in material thickness and weight.