PURPOSE: To improve productivity of a cover of excellent strength by parting the cover into two freely folding cover parts to be fixed to a protection device housing, and embedding a reinforcement insert of a metal plate in each cover part.

CONSTITUTION: A totally arc-shaped cover of a gas bag collision-protection device on a driver's side comprises two rectangular cover parts 10, 12, and a frame 14 surrounding these. Each cover part 10, 12 has an outer edge 10A, 12A in a protruded arc form. Each cover part 10, 12 comprises an outer granular plastic plate, and foam plastic around it in which a reinforcement insert 18, 20 is embedded, and the cover parts 10, 12 are coupled with each other at center edge zones along a tearing line 22 by weakened wall part thin pieces. The reinforcement insert 18, 20 comprises metal such as aluminum, and it gets out of an outer edge zone of the cover part 10, 12 to end at a lug of a fixture part 26, 28.