A holding socket for a fastener having a nut arrangeable on a threaded element, and a washer located between the nut and an object, the holding socket has a body having two opposite ends with a first end connectable to a part of a power tool and a second end which is axially spaced from the first end and connectable with the washer so as to hold the washer against rotation, and a locking element located in an area of the second end of the body and displaceable transversely to the body between a position in which it is located axially between the second end of the body and the nut and therefore prevents a removal of the socket from a fastener and another position in which it is no longer located axially between the second end of the body and the nut, and therefore allows withdrawal of the socket from the fastener.