PURPOSE: To obtain a stay for window which meets market demands or standards, can resist to all invasions whatever the invasions are, and can be manufactured easily.

CONSTITUTION: A stay for window is provided with a frame attaching member 10 and a sash attaching member 11 and both or at least one of the members 10 and 11 is die-cast. A short arm 13 and a long arm 12 are pivotally attached to the members 10 and 11 through bearings 14 and 15. The head lock 24 of an external-pressure lock (head lock) mechanism is supported by the sash attaching member 11 and protruded in the direction perpendicular to the longitudinal direction of the member 11. When the stay reaches the position corresponding to the closed position of a window, the head lock 24 is engaged with an external-pressure resisting section (head stop) 20 protruded from the frame attaching member 10 through engaging surfaces 22 and 25.