There is provided: an optical sheet, which has excellent productivity while maintaining an optical performance and can reduce a manufacturing cost; an image source unit; a display device; a method for producing an optical sheet; and a method for manufacturing a display device.An optical sheet 10 is disposed on an observer side relative to an image source and comprises a plurality of layers that control light emitted from the image source to emit the light on the observer side, wherein at least one of the plurality of layers is a base material layer 16; one layer disposed on one side of the base material layer is an optical functional sheet layer 11, which comprises prisms 12 being arranged in parallel along the sheet surface of the optical sheet whereby light can be transmitted and light-absorbing parts 13 being arranged in parallel between the prisms whereby light can be absorbed; one layer disposed on the other side of the base material layer is an adhesive layer 17; and an adhesive layer is not provided on a side surface of the optical functional sheet layer facing the side disposed with the base material layer.