An apparatus to clamp and support a device includes a chassis, two clamping members, an elastic element, a driving pole, a cam, and a cover. The chassis includes a blocking tab. The two clamping members include a first clamping member and a second clamping member. The elastic element is located in a receiving hole. The driving pole is rotatable relative to the chassis. The cam can engage with the driving pole, and includes a first cam flange abutting to a first engaging post of the first clamping member. The cover is mounted to the chassis. The two clamping members and the cam are located between the chassis and the cover. The cam is rotated by the driving pole. The first cam flange urges the first engaging post to move the first clamping member away from the second clamping member.