To provide a new side chest for a study desk capable of easily selecting a height by a manual engagement/disengagement operation and an inclined raising/lowering operation capable of performing sequentially to the engagement/disengagement operation all at once and provided with an upper surface plate exhibiting functions of forming a personal computer mount part and a bookshelf part and vertically movable along the rearward inclined line.

This side chest is provided with the upper surface plate 13 provided liftably within a range higher than the top plate 2 of a study desk and higher than the height of the personal computer or the vertical width of a book in the top surface of a side chest body 6, multistage lock receiver parts provided in respective left/right fixed leg members in a vertically sequential multistage disposition along the rearward inclined line, lock hanger parts alternately engaged with/disengaged from lock parts of the respective stages provided in respective left/right movable leg members, and manual disengagement operation parts 21 positioned in lower parts of the left/right edge parts of the upper surface plate 13 and provided in a release member so as to be manually liftable along the rearward inclined line with the edge parts.