To provide an opening and closing structure of a glove box which allows an arm of a lock mechanism arranged between a box body and a lid to smoothly slide to a retainer at the support leg side of the lid supporting the arm and can reduce production cost.

The glove box 5 is openably/closably supported by an instrument panel, and the lock mechanism 13 is configured of the arm 16 and an operation part and is configured to be freely switched to a lock state where the arm 16 engages with a part 14H to be engaged and a lock release state where the arm 16 releases engagement with the part 14H to be engaged. An arm insertion hole 19H is formed at a support leg 19, a sliding part 15S where the arm 16 slides is arranged in the arm insertion hole 19H, and a protrusion 22 to allow the tip part 19A of the support leg 19 to come into point-contact with or to come into line-contact with is protruded at the box body 6 when the box body 6 and the lid 8 are vibratingly welded.