A support for a musical keyboard instrument has a first leg, a second leg and an adjuster. The first leg is pivotally connected to the second leg and a rod is formed in a sidewall of the second leg. Two first spiral surfaces are respectively formed in a free end of the rod and the adjuster is provided adjacent to the rod. The knob is formed on the adjuster and has two second spiral surfaces respectively formed thereon and mated with the first spiral surfaces. When the second spiral surfaces are locked by the first spiral surfaces, the first leg can be adjusted relative to the second leg. When the first spiral surfaces are engaged with the second spiral surfaces, the fist leg is secured in position on the second leg.