PURPOSE: To provide a joining structure for parts, which is simple in constitution, and is excellent in assembling properties, appearance and mounting accuracy.

CONSTITUTION: One part is provided with a first butting face 2d which is perpendicularly intersected with a first coupling section 2c, and with a first pin 2b and a second pin 2a provided on the first butting face or on a face close to the aforesaid butting face in parallel with the first coupling section 2c. And the other part is provided with a second coupling section 3c coupled with the first coupling section 2c, a second butting face 3e perpendicularly intersected with the aforesaid second coupling section, a first press-in hole 3d which forms press-in relation with the first pin 2b while being rattled roughly in the radial direction on the aforesaid second butting face or on a face close to the second butting face at a position corresponding to the first pin 2b, and with a second press-in hole 3a which forms press-in relation with the second pin 3a while being rattled roughly in the radial direction at a position parted from the second butting face 3e by a specified distance L1 capable of absorbing the relative position errors of the first and second pins.