An application method of applying a film F having a main portion 71, an extended portion 72 connected to a first end 71x of the main portion 71, and an extended portion 73 connected to a second end 71y opposing the first end 71x in the main portion 71 to a base material by an application device having an application mechanism, including the steps of: pressing the extended portion 72 using the application mechanism; applying the main portion 71 to the base material by moving the application mechanism that presses the extended portion 72 from the extended portion 72 to the extended portion 73 via the main portion 71; and stopping the application mechanism moved to the extended portion 73 and separating the application mechanism from the extended portion 73.