To provide a leg apparatus of a desk which has sufficient strength and the increased number of components that can be shared by an end part leg part and an intermediate part leg body while securing the degree of freedom in the design of a leg body resulting in cost reduction.

In the leg body, an upper support member 31 and a lower support member are attached to upper and lower ends of a sheet metal-processed leg plate part 30, and the leg plate part is composed of a body plate 41, an upper reinforcing member 43 and a lower reinforcing member. The body plate has a roughly U-shaped on cross section having both side face plates 41A and a rear surface plate 41B; upper and lower bend edges 41C are formed on both side face plates, and a vertical duct 34 is formed at the rear part of one or both side face plates. The upper reinforcing member and the lower reinforcing member are the same member, are in bilateral symmetry, and are composed of an abutting part 46 of a narrow horizontal width extended from a horizontal center part to the rear part at the rear end of a mounting part 45 for receiving the upper support member or the lower support member. The upper reinforcing member and the lower reinforcing member are inserted between both side face plates of the body plate from the front and are welded to both side face plates while abutting the rear end of the abutting part to the rear surface plate.