To apply a sheet material to a planar applied object while inhibiting the occurrence of appearance defects.

A sheet application device includes: a treatment chamber 10; an applied object holding part 20 which is provided in the treatment chamber 10 and includes a holding surface Sh for holding a planar applied object 6; and a sheet material holding part 30 which is provided in the treatment chamber 10, has an adhesive surface Sa which holds the sheet material 5 in a planar manner, and may move so as to move close to or separate from the holding surface Sh of the applied object holding part 20 in a state that the adhesive surface Sa faces the holding surface Sh of the applied object holding part 20. The sheet material holding part 30 is moved close to the holding surface Sh of the applied object holding part 20 in a state that the decompressed atmosphere is maintained in the treatment chamber 10 thereby causing the sheet material 5 held by the sheet material holding part 30 to closely adhere to the applied object 6 held by the applied object holding part 20.