PURPOSE: To obtain the title material having a high sensitivity and a high resolution to an actinic radiation and used in the production of semiconductor elements, magnetic bubble elements, etc., by adding a specified o-naphthoquinone compound to a specified silicone resin.

CONSTITUTION: This pattern forming material is obtained by adding an o- naphthoquinone compound of formula V (wherein Z is OH, OCl, OF, formula VI, formula VII, formula VIII, formula IX or the like, and x and y are positive numbers) to a silicone resin of formula I or II {wherein X is formula III, formula IV [wherein R is a (substituted)hydrocarbon group] or COOH, R'WR'''' are each OH, an alkyl or a phenyl, l, m and n are each 0 or positive integer provided that l and m must not be 0 at the same time, and p is a positive integer}. This material can form a negative pattern of a high sensitivity and a high resolution by irradiating it with an actinic radiation such as ultraviolet rays in a vacuum, an inert gas or air and optionally heating it, irradiating the entire surface with light and developing it with an alkali.