Abstract: A one-touch tent flysheet having an edge portion is fixed to the ground in a state in which the one-touch tent flysheet covers a tent to protect the tent from an external environment, includes a waterproof cloth installed to cover the tent, a tunnel-type pole which is fixed to the waterproof cloth to allow the waterproof cloth to stand in the form of a tunnel when the flysheet is installed and which is formed in a ring shape and bent so that a pair of first points facing each other press against the ground and a pair of second points facing each other, which are at a right angle from the first points, are located at the highest height level, and a fastening member configured to connect and fix portions of the tent and the flysheet to allow the flysheet to be attached to or detached from the tent.