To provide an innovative simple-mounting type curtain of high commercial value, when mounting it to, for example, a window opening part, capable of insulating heat taken from not only glass surfaces but also metal window frames, preventing inflow of air cooled by the metal window frames and the glass surfaces and of cold air entering from a clearance between the metal window frame and the metal window frame, into an indoor space and exerting superior heat-insulating property despite a constitution being mounted easily.

In this simple-mounting type curtain, an elastic strut bar 2 laid between and fixed to mounting portions 1 by press-contacting both left/right ends includes a sheet part 3 covering the mounting portions 1 and shutting off an air flow, and a foldable lower fold part 4 and side fold parts 5 abut on the lower bottom between the left/right mounting portions and mounting portions in a bent state are provided at the lower part and the side parts of the sheet part 3.