A setup method of top tension devices which have adjusting members for applying electrically controllable tension to yarns and are provided on a flat knitting machine , being characterized in that a measuring step (S1), performed outside a flat knitting machine , for measuring and storing an input value for each yarn to an adjusting member for applying a desired tension to said each yarn is performed, wherein said each yarn (10is fed to and drawn by a drawing member through a tension sensor and the adjusting member , wherein the drawing member , the tension sensor , and the adjusting member are provided out of the flat knitting machine , wherein said input value to the adjusting member is measured with a dedicated measuring device when the tension to said each yarn is a desired value, and wherein said input value is stored, that a step (S2) for storing elements that contact or influence said each yarn in each yarn feeding route from a top tension device to a carrier of said each yarn and comprise: species of yarn feeding objects , at an upper stream position of the carrier along a direction of yarn feeding, to which said each yarn is fed by the top tension device ; the number of eyelets through which said each yarn passes in each yarn feeding route; and a degree of bending said each yarn by the eyelets in said each yarn feeding route is performed, and that a setup step (S3) for correcting said input value on the basis of the elements in order to transform said input value to a setup value for the adjusting members in each yarn feeding route and applying the setup value to the adjusting member in each yarn feeding route by a controller in the flat knitting machine is performed. a measuring step (S1), performed outside a flat knitting machine , for measuring and storing an input value for each yarn to an adjusting member for applying a desired tension to said each yarn is performed, wherein said each yarn (10is fed to and drawn by a drawing member through a tension sensor and the adjusting member , wherein the drawing member , the tension sensor , and the adjusting member are provided out of the flat knitting machine , wherein said input value to the adjusting member is measured with a dedicated measuring device when the tension to said each yarn is a desired value, and wherein said input value is stored, that a step (S2) for storing elements that contact or influence said each yarn in each yarn feeding route from a top tension device to a carrier of said each yarn and comprise: species of yarn feeding objects , at an upper stream position of the carrier along a direction of yarn feeding, to which said each yarn is fed by the top tension device ; the number of eyelets through which said each yarn passes in each yarn feeding route; and a degree of bending said each yarn by the eyelets in said each yarn feeding route is performed, and that a setup step (S3) for correcting said input value on the basis of the elements in order to transform said input value to a setup value for the adjusting members in each yarn feeding route and applying the setup value to the adjusting member in each yarn feeding route by a controller in the flat knitting machine is performed. <EOS>