A pellicle is proposed in which the frame is formed with an external horizontal slit for the purpose of receiving a pressing means, which can urge the pellicle to be adhered to a photomask, in which the slit forms a vertically protruding part of a thickness of 5-30% of the width of a pellicle frame main body and a horizontally protruding part of a thickness of 0.3-1 mm; also the method of adhering the pellicle to the photomask is proposed.