To provide a warp tensioner needing no support beam extending throughout the crosswise direction of a web, and needless to surely conduct transmission perfectly free from clearance for performing extremely minute longitudinal actions of a tensioner element.

The warp tensioner has a tensioner element (3), at least one support element and a servomotor (2). The rotor (6) of the servomotor (2) has a scheme serving as a part of the support element or the tensioner element (3). The scheme affords a structure with low inertia and sets the actual value of warp tension based on motor current and the position of the tensioner element (3).