There is provided an apparatus used for forming a pattern on a substrate by photolithography with electron beams, the apparatus including (a) an aperture formed with at least one opening through which electron beams are to pass, and (b) a holder for fixedly supporting the aperture therewith by means an adhesive, at least one of surfaces of the aperture and the holder at which the aperture is adhesively fixed to the holder, being formed with at least one groove for excessive portion of the adhesive to flow in. When an aperture is fixed onto a holder with an adhesive, an adhesive may be excessively applied on a surface of the aperture or holder. However, in accordance with the above-mentioned apparatus, since excessive adhesive is pooled in the groove, it is possible to avoid the excessive adhesive from being forced out to the opening of the aperture, and thus, it is possible to avoid forming an incorrect pattern on a photoresist film.