To provide a net holding mechanism which makes engagement of a cover and a bracket for net engagement less likely to be released.SOLUTION: A net holding mechanism includes: a net holding bracket including a net holding part which holds an upper end edge part of a net, the net holding bracket attached to a roof side rail; a cover 60 attached to the net holding bracket through an opening provided at a roof head lining; and engagement state maintaining means (for example, reinforcement parts 71, 74). The cover 60 includes: a cover body part 61 which covers a peripheral edge part of the opening of the roof head lining from a vehicle inner side and is formed with an insertion hole 61h into which the upper end edge part of the net may be inserted; and engagement claws 66, each of which protrudes penetrating through the opening of the roof head lining from the cover body part 61 and engages with the net holding bracket. The net holding bracket is formed with engagement holes with which the engagement claws 66 engage. The engagement state maintaining means (for example, the reinforcement parts 71, 74) inhibit the engagement claws from being released from the engagement holes.SELECTED DRAWING: Figure 6