A bolt-locking apparatus includes a plurality of fitting members 2 and 3 which are relatively non-rotatably fitted to heads of a plurality of bolts 5, and an engaging member 4 fitted to the plurality of fitting members 2 and 3 such that the engaging member 4 straddles the fitting members 2 and 3. Outer peripheral surfaces 2b and 3b of the fitting members 2 and 3 are non-circular in shape. The engaging member 4 includes a plurality of engaging holes (non-circular engaging portions) 8a and 8b which correspond to the non-circular outer peripheral surfaces 2b and 3b of the plurality of fitting members 2 and 3.