To provide a shelf device of a studying desk in which a shelf board can be disposed for a whole left and right directional length of the top plate of the studying desk above its rear portion, an arranging space for an electronic device such as a personal computer can be formed in left or right half of the rear portion of the top plate, and the condition can be altered according to a using purpose without substantially reducing a storing space for books even though the arranging space is formed.

An immovable partitioning board 5 is fixed to a center of both side plates 1A, 1A, respective supports 9, 9 are made attachably and detachably attachable to the upper and lower stages of the inner face sides of both the side plates facing the inner space and both the face sides of the immovable partitioning board 5, shelf boards 6, 7 have the substantial same lateral width and can be supported by the same supports, and the partitioning board can be attached to the shelf boards in a high longitudinal directional arrangement and a lower lateral directional arrangement.