Abstract: A tensioner for a hybrid electric vehicle adjusts tension of the belt which is provided to synchronize rotation of a pulley of a starting motor shaft and rotation of a pulley of a crankshaft. The tensioner for a hybrid electric vehicle may include: a base arm, a driving arm pivotably connected with the base arm, and a driven arm pivotably connected with the base arm. The tensioner further includes an actuator operating so as to autonomously vary an entire length so that one end thereof is fixed to the base arm and the other end thereof is connected with the driving arm; a first pulley rotatably connected with the first pulley connecting portion or the driving arm and rolling while contacting the belt; and a second pulley rotatably connected with the second pulley connecting portion of the driven arm and rolling while contacting the belt.