To attempt an enlarged space for office work or study and activate one's brains, thus, helping maintain one's good health by equipping a desk with two top boards up and down.

A desk is equipped with two-step upper and lower top boards 1, 2. The upper and lower top boards 1, 2 are divided into innermost parts 1a, 2a and foreground parts 1b, 2b, respectively, and the foreground parts 1b, 2b of both upper and lower top boards are formed in foldable manner by hinges. When the lower top board 2 is used, the foreground part 1b of the upper top board 1 is folded and used just like an ordinary desk through the use of a chair 3 to sit down. As the foreground part 1b of the upper top board 1 is folded down, the effect caused by a shaded light becomes less. When the upper top board 1 is used, the foreground part 2b of the lower top board 2 is folded down and the user uses the upper top board 1, standing in front of the desk. When the foreground part 2b of the lower top board 2 is folded down, the front of the legs of the user are released for that space; thus, an extent of freedom in a standing posture can be heightened.