Abstract: A release piece for a drill string is adapted to disengage upon activation in connection with a bit stuck in the lower portion of the bore hole during drilling. An elongated tubular release piece (10a, 10b) is, at the ends (12a, 12b) thereof, formed to be coupled into the drill string, upstream the bit. The drill string release piece comprises two substantially coaxial sleeve parts (10a, 10b) disposed in the continuation of each other and screwable together, the sleeve parts (10a, 10b) internally being provided with axially directed locking device (16a, 16a′, 16b, 16b′). An internal, axially displaceable locking device (18) has locking device (28′, 28″) capable of cooperating lockingly with the locking device (16a, 16a′, 16b, 16b′) of both sleeve parts (10a, 10b), the locking position being maintained by a spring (22).