PURPOSE: To carry out all work on an upper flange of a beam by fixing a safety net installation fitting free to disconnect by way of inserting it into a clearance between an upper side plate material and a sandwiching plate on the upper flange of the steel beam.

CONSTITUTION: A downward L shaped member is formed of an upper side plate material 1 and a hung wall 2 hanging down from one end of this upper side plate material 1. Additionally, an upward L shaped member is formed of a sandwiching plate 3 and a vertical wall 4 rising upward on this one end. Joint of both of the L shaped members is fastened by jointing a horizontal flange 5 of a top part of this vertical wall 4 on a lower surface of the upper side plate material 1. This installation fitting is installed on an end part of an upper flange 7 of a beam 10, and a ring type installation rope provided on an end part of a safety net 11 is suspended across above the upper flange 7 in a hook clearance formed between the hung wall 2 and the horizontal wall 4. The more load the safety net receives, the more firmly the installation fitting joints with the upper flange, and the safety net is never disconnected.