A fastener for superimposing and fastening two sheets of plate-like members, wherein at least one of the plate-like members has a hole formed therein, includes a pair of U-shaped accommodating portions adapted to be inserted with end portions of the two sheets of plate-like members; a pair of connection portions respectively connecting the pair of accommodating portions; a pair of engagement pieces extending from the pair of connection portions in an insertion direction of the plate-like members; an engagement portion formed in each of the pair of engagement pieces, adapted to engage with the hole; and a wobbling suppressing mechanism disposed adjacent to the pair of engagement pieces, and extending from each of the pair of connection portions in the insertion direction of the plate-like members for engaging with the hole.