According to the present invention is a fastening band, forming the body 2 of the band shape having a predetermined width, first, the both sides of the open side of the body (2) is bent so as to project to the upper part and the third coupling portion 4, 14 and the first and the third tightening part (4) (14) a position between the fastening groove portion 8, the cut part of the body (2) is formed projecting to the upper part by a punching process presented by prior tightening wound to form a second connection part 6 of the dome-shaped that the two sides are opened, and turning the body 2, a circular first engaging portion 4 and the fastening the first fastening part (18) and , by the connection between the forming guide the incision part of the body 2 in the front-rear end recess 16 and guide recess 16 be formed to project downward by the punching process the second fastening portion (6 domed ) to form a second engagement portion 20 to be entered into engagement with the seating as soon a fastening groove (8) of the support firmly by the contact surface when fastening dome-shaped coupling portion and the engagement portion Configuration is has the effect capable of preventing becomes bent portion concluded after tightening by increasing the tightening portion supporting force for supporting the engagement during tightening of the tightening band (1) loosening the fastening, the fastening portion and the engaging portion bearing supported in surface contact such that which will have high rigidity as, the effect capable of preventing loosening the fastening with the box preventing erroneous assembly becomes damaged or bent fastening portion after fastening by the constant pressure accordingly.