To provide a bearing fixing device for a construction machine capable of stopping the rotation of a nut member without needing to tighten the nut member after reaching regular drag torque to stop fastening of the nut member.

The bearing fixing device provided at a swing device 6 of a hydraulic shovel 1 includes the nut member 21 having two threaded holes 21C and pressing bearings 19, 20 to a housing 15; a lock plate 31 having nine through-holes 31B and a spline part 31A engaged with a spline part 10C formed at a swing output shaft 10, and fixed to the nut member 21; and two bolts 27 inserted in the through-holes 31B and screwed into the threaded holes 21C to fix the lock plate 31 to the nut member 21. The lock plate 31 includes the nine through-holes 31B in a circumferential direction centering on the axis of the swing output shaft 10, at the pitch β(θ) preset in relation to the pitch P(θ) of the spline part 10C.