The invention discloses a tension machine, which is applied to the field of electric power construction. The tension machine comprises a bottom supporting beam, a tension wheel and a wire passing wheel, wherein the bottom supporting beam is arranged on a chassis of the tension machine; the wire passing wheel is located under the tension wheel and is at least divided into two sections, and the two sections are connected by a supporting transverse rod in a penetrating way; supporting pieces are arranged above the bottom supporting beam; semicircular grooves are formed in the upper parts of the supporting pieces; the supporting transverse rod is arranged in the semicircular grooves. According to the tension machine disclosed by the invention, after the supporting piece is additionally arranged, because the supporting pieces have supporting and force bearing functions on the supporting transverse rod and the wire passing wheel, the situation that due to an insufficient tension force during a normal working state of the tension machine, when a leading wire on the tension wheel descends to be in contact with the wire passing wheel, the supporting transverse rod is enabled to bend and deform due to excessive stress on the wire passing wheel, and the wire passing wheel and the leading wire are abraded can be effectively prevented, thus the service life of the wire passing wheel and the leading wire can be effectively prolonged, and the maintenance cost can be reduced.