PURPOSE: To automatically properly determine a cooling time by providing a means to determine a cooling time of a weld part of a strap linked with an automatic welding means.

CONSTITUTION: A control circuit 10 for a tool for a hand strap comprises a circuit part 11 to automatically provide tension to a strap, a circuit part 14 to delay welding of the strap till a proper tension is obtained around an article, a circuit part 16 to automatically determine a time of a welding process, and a circuit part 18 to automatically determine cooling of a weld part. Air from a cylinder 52 in the circuit part 18 is discharged through a variable orifice 54, discharge of air from the cylinder 52 is controlled by a valve 50, and a cooling time of the weld part in the strap is determined.