An adjustable desk includes a desk board, a supporting unit, and a first adjusting unit. The desk board includes front and rear ends. The supporting unit disposed between the desk board and the ground includes a first leg pivotally connected with the front end. The first adjusting unit mounted between the desk board and the first leg includes a screw shaft, at least one linkage, and at least one level. The linkage is engaged screwedly with screw shaft. The level pivotally connected between the linkage and the rear end. While the screw shaft is rotated, the linkage is moved axially between two ends of the outer screw portions to drive the level pivoting with respect to the screw shaft. The desk board is pivoted with respect to the first leg to adjust a slope angle formed between the desk board and the supporting unit steplessly without tools.