A tension spanner comprises a holding portion having an axial receiving hole at one end thereof; an outer periphery of the holding portion being formed with a plurality of textures for being held steadily; an upper periphery of the holding portion having a plurality of numbers for indicating the position in alignment; and a handle having an inner rod and an outer tube; one end of the inner rod being installed with an axial rolling ball; the outer tube having a receiving space; the inner rod in the outer tube can swing slightly in the receiving space of the outer tube; an outer side of the outer tube being formed with a scale; and an inner sleeve, an outer sleeve, an elastic body and a supporting post are received in the receiving space of the outer tube.