A hinge adjuster includes a first frame, at least one locking piece, at least one spring component, at least one second frame and a pair of cover. The first frame defines at least one locking hole including a first accommodating hole and a second accommodating hole. The locking piece is slidably placed in the first accommodating hole for engaging with the first accommodating hole or the engaging notch alternatively. At least one groove for engaging with the locking piece is configured on a pivoted portion of the second frame, which includes a flat portion, a dentiform portion, and an end portion. And the locking piece is protruded from the locking hole and contacting with the flat portion, the dentiform portion or the end portion selectively. The hinge adjuster has strong supporting capability and can achieve a cyclic adjustment of angles, and the operation is simple and convenient.