To provide a detailing structure of a window, which can give an impression of a luxury residence even in the use of an exterior wall surface material with a small plate thickness.

In this detailing structure of the window, an outdoor surface is retreated in an indoor direction from an exterior wall surface, and a gap is provided between the outdoor surface and the exterior wall surface material 2, so that a window frame 31 can be mounted in an opening 21 of an exterior wall; an upper coupling material 32 is mounted at an edge of an upper gap between the material 2 and the window frame 31; a lower water drip 33 is provided at an edge of a lower gap; side coupling materials 34 are mounted at edges of gaps on both sides; and an end surface of the material 2 and the gaps thereof are closed.