PURPOSE: To prevent collapse of a load stack by preventing the first belt from slipping out of a winding shaft when cargo fastening is released.

CONSTITUTION: A belt cargo fastening machine has a belt length adjusting mechanism 8 composed of a rolling-up shaft 9 which fixes the base end part side of the first belt 5 to a winding shaft 6 and rolles up the middle of the loose end side of the second belt 7 in the other side of a main body 1 and cannot rotate but can displace in a lengthwise direction of the main body 1 and a fixing rod 2 which is opposed to the rolling-up shaft 9 while situating in front of this rolling-up shaft 9 and sandwiches and fixes the second belt 7 between it and this rolling-up shaft 9. Thereby, tension can be applied beforehand to the belts 5 and 7 by adjusting length of the second belt 7, and winding for fastening becomes possible by reducing a winding quantity of the first belt by means of an operation lever 10, and when this winding and fastening 15 released, even if the first belt 5 is wound back by not less than the winding quantity, since the first belt 5 does not slip out of the winding shaft 6, even if collapse of a load stack is caused at that stage, the collapse of load stack beyond that can be prevented.