To provide a connecting part structure for pipe, which improves sealing property while preventing axial slip between a first pipe and a second pipe, and allows a clamp to be reduced in size.

The connecting part structure for pipe comprises: a first pipe 1 including a first projection part 11 formed by turning up a pipe end toward an outer circumferential surface; and a second pipe 2 having an outer diameter insertable into the first pipe 1 and including a second projection part 21 having substantially the same height as the first projection part 11, which is formed by turning the middle of the pipe in S-shape while leaving an insert part 22 to be inserted into the first pipe 1 at the tip. The structure also comprises a clamp 3 including: a shallow annular groove 33 having a height smaller than the protruding height of the first projection part 11 and the second projection part 21; both side walls 33a and 33a constituting the annular groove 33 which are formed in outwardly tapered faces; and both the outwardly tapered faces abutting on both edge parts of the first projection part 11 and the second projection part 21.