To provide a band tying machine that can provide accuracy in positioning for stoppage of a cam mechanism part while being capable of operating in the normal and reverse rotations.

A band tying machine 40 is equipped with a band feeding mechanism 3 that feeds a band 1, a band tightening mechanism 4 that pulls back the band 1, and a band joining mechanism 5 that applies heat sealing to the band 1. The band joining mechanism 5 is equipped with a cam mechanism part 21 comprising of a tip clamping cam part that clamps the tip of the band 1 fed out by rotative driving of a camshaft 21a, a band releasing cam part that releases the band 1 from a guide course 2, a tail end clamping cam part that clamps the tail end side of the tightened band 1, a heater cam part that inserts and takes out a heater into and from a position between the bands 1, a pressure sticking cam part that sticks with pressure the bands 1 heated by the heater, and a cutter cam part that cuts the tail end part of the band 1. A driving source that drives the camshaft 21a in rotative motion is an encoder-equipped servomotor 46, and a control part 45 that controls the driving of the servomotor 46, based on feedback of rotative positions of the cam shaft 21a, is provided.