PURPOSE: To obtain the photosensitive dry film which can maintain a dampproof effect stably over a long period of time by providing films having dampproofness in the side face pats of the photosensitive dry film.

CONSTITUTION: The films having the dampproofness are formed in the side face parts of the photosensitive dry film. These films are more particularly preferably three-dimensional siloxane films and the method of forming such films is executed by applying the siloxane compd. expressed by formula I on the side face pats of the photosensitive dry film and drying the coating, thereby forming the three-dimenisional siloxane films. In the formula I, R' and R' respectively independently denote -H, -CH3, -C2H5, -C5H6, -CH=CH2, -OCH3, -OC2H5, -OC3H7, -NR2; X and X' respectively independently denote -OH, -OCOCH3, etc. R is 1 to 3C alkyl group. Cold flow is completely prevented in this way and, therefore, the photosensitive dry film which is free from a change with lapse of time is obtd.