PURPOSE: To use a freely foldable sunroom even in a cold area where a station ary sunroom can not be used because of snow fall.

CONSTITUTION: Freely folding side wall panels 30 which are jointed to vertical frames 12, 22 at the one side thereof by hinges 70 and connected to each other with hinges 70, are arranged between the inside frame 10 fixed to a building and the outside frame 20 forming the front opening. Further, roof panels 40 and floor panels 50 are jointed to the upper frame 11 and the lower frame 13 of the inside frame 10 with hinges to close the upper end and the lower end of the outside frame 20 and the side wall panels 30 by these roof panels 40 and the floor panels 50. And an opening member 60 is arranged at the front opening of the outside frame 20 to be able to freely fold the sunroom A. The sunroom can be folded and expanded so as to press or draw the outside frame 20 and raise or tumble the roof panels 40 and the floor panels 50.