An adjustable frame includes a first support, a second support, two third supports and two assembling members. The second support is disposed on the first support, and the second support is slidable relative to the first support along a first direction. The two third supports are disposed on the first support. At least one of the two third supports is slidable relative to the first support along a second direction perpendicular to the first direction for adjusting a distance between the two third supports. The two assembling members are respectively disposed on the two third supports, and a distance between the two assembling members is adjustable by movement of the at least one of the two third supports.