A holding device includes a U-shaped base fixed on a wall and including a first protrusion and a second protrusion. A receiving space is defined between the two protrusions. The first protrusion has a hole defined in an inside thereof and a clamping member is eccentrically received in the first protrusion and a part of the clamping member is movably extended through the hole and protrudes into the receiving space. A shank of a tool is received in the receiving space and clamped by the clamping member and the second protrusion.