A novel photosensitive ternary complex formed from phenol-formaldehyde resin (PR), sodium dodecyl sulfate (SDS), and diazo resin (DR) was developed. In the presence of SDS, PR remains soluble in water when its solution is neutralized. The PR-SDS-DR ternary complex forms when DR is added to the PR-SDS solution. The ternary complex dissolves in polar solvents such as dimethylformamide and is sensitive toward UV light or heating. It was confirmed that the ionic bond of -SO4 +N-2-between SDS and DR converts to a covalent bond after the decomposition of the N-1(2)- group under UV irradiation or heating. As a result, the solubility of PR-SDS-DR changes dramatically; that is, after treatment with UV light or heating, PR-SDS-DR becomes insoluble in polar solvents.