SCREEN DEVICE AND HELMET

This screen device configured to be attached to a helmet comprises a supporting part and a combiner. The supporting part includes a rail part for supporting the combiner. The combiner includes: a projection plane on which an image projected from a projection part attached to a helmet is projected; and a supported part supported by the rail part. The rail part supports the supported part such that the supported part can move between a display position at which the projection plane is disposed in front of a wearer of the helmet and a retracted position at which the projection plane is retracted from the front of the wearer. The supporting part further includes a positioning part that positions the supported part supported by the rail part. The positioning part is configured to position, through external operation on the positioning part, the supported part at at least one of the display position and the retracted position.