To provide a book or information device mounting table for bed, applicable to reading or enjoying the information device on the bed, and capable of being stored compactly when not used; and its support device.

A semi-circular arm 11 extending from the head to the foot of the bed is turnably journaled to a slider 21 engaged with a base 22 fixed to a component member 1 on either side of the bed by a dovetail groove 23, and the arm 11 is held at an arbitrary angle by an arm support 13 engaged with both the arm 11 and the slider 21. The slider 21 engaged with the base 22 by the dovetail groove 23 can be moved upward/downward along the base 22. When the mounting table 71 is not used, the arm 11 is raised and the slider 21 is brought down to be stored. The book or information device mounting table 71 can be fixed at an arbitrary position on the arm 11 and can be fixed turnably with the arm 11 as the axis. The mounting table 71 is engaged with the arm 11 by a joint 60 so that the direction to the arm 11 can be freely changed and can be turned around the axis perpendicular to the flat plane of the mounting table 71.