To provide a cover member attaching structure capable of easily and stably attaching a cover member to the depressed part formed to the surface of a hollow molded product such as an air spoiler and preventing the fall-off of the cover member from the depressed part even when the hollow molded product is deformed.

A cover member attaching boss part 12 is formed to the central part of the bottom part 11b of the fixing depressed part 11 formed to the upper surface wall part 1a of an air spoiler and the peripheral bottom part 11b of the boss part 12 is pinched off at the rear surface wall part of the spoiler and the boss part 12 is liquidtightly molded along with the hollow interior of the spoiler. A through-hole 12b is formed to the peripheral wall part 12a of the boss part 12 containing the bottom part 11b and the engaging pawl piece 2C of a cover member 2 is engaged with the through-hole 12b to fit and attach the cover member 2 to the depressed part 11. In this attaching state, the cover member 2 is stably attached because the central part thereof is supported on the upper surface of the boss part 12.