To provide a battery housing structure capable of attaching a cover through one action and surely preventing the play of the cover with a simple constitution by bringing a part of the cover into elastic contact with a part of a grip part, thereby eliminating the play of the cover with the elasticity of the grip part.

When a battery 18 is exchanged for another one and then, a battery housing 22 is closed with the cover 27, an engaging projection 27c is depressed toward an engaging recessed part 24 while an engaging projection 27b is engaged with an engaging groove 23. Thus, the engaging projection 27c is inserted into the battery housing 22 while being deflected, and engaged with the engaging recessed part 24. At this time, since the engaging projection 27b comes into elastic contact with the part facing the engaging groove 23 in a rubber grip part 15, the cover 27 is applied with elastic force through the engaging projection 27b to remove the play in the state where the abutting surface 27d of the engaging projection 27b is abutted on the rear side end face 22a of the battery holder 22. Therefore, the occurrence of the play of the cover 27 is prevented and the cover 27 can be surely made in close contact with the opening part of the battery housing 22.