Holder having adjustable clamping orientation

A holder having an adjustable clamping orientation, for firmly positioning a mobile electronic device on a plate of an object, and the holder comprising:

• a clamping assembly, comprising a first clamping plate extended forwardly from a front end thereof, a side of the first clamping plate movably connected with a second clamping plate, and the first clamping plate and the front end of the second clamping plate cooperatively forming a clamping head to clamp the plate;
• a support assembly, having a front end pivoted to a rear end of the clamping assembly and a side edge pivoted with a support arm extended therefrom, wherein a pivoting shaft between the support arm and the support assembly is vertical with a pivoting shaft between the support assembly and the clamping assembly, so as to enable the clamping assembly to be rotatable relative to the support assembly and enable a free end of the support arm to be rotatable away from or close to the clamping assembly, whereby the free end of the support arm is abutted with a lower edge of the object while the clamping head is clamped and positioned on the plate;
• and
• a holding seat, having a front end rotatably fastened with a rear end of the support assembly, and comprising a positioning member disposed at a rear end thereof, so as to firmly position the mobile electronic device at the rear end of the holding seat.