To provide a drawer rail unit which can make effective use of space by ensuring the smooth movement of drawers over a long period.

This unit includes a baseplate 22 spliced to the inner surface of a side panel 11 and a plurality of projecting rails 25 provided on the baseplate 22, and drawers 21 are longitudinally movably laid by forming guide grooves 26 between the projecting rails 25. In the area of the projecting rails 25, locking holes 27 are formed and a groove forming piece 30 is joined to the upper end of the baseplate 22. A guide groove which works in substantially the same way as the guide groove 26 is formed between the groove forming piece 30 and a plane immediately therebelow.