Waterproof connecting structure for pipe

A waterproof connecting structure for a pipe for connecting an intake passage of an internal combustion engine and an external gas detector to convey gas into the intake passage, the structure comprising:

• a connecting space to which the pipe is connected, wherein the connecting space has a larger diameter than the pipe;
• a partition wall formed between the intake passage and the connecting space, wherein the partition wall includes a hole on the side wall of the intake passage for placing the intake passage and the connecting space in fluid communication, wherein the hole has a traverse cross-sectional area having a shorter length and a longer length, wherein the hole is offset to extend along an edge of the partition wall, wherein the hole extends longer along the edge and extends shorter in a radial direction of the partition wall, wherein the edge on which the hole extends is an edge including a lowermost part of the partition wall relative to gravitational direction.