A positive working photosensitive polymer based on poly(2,6-dihydroxy-1,5-naphthylene) (PDHN) with 1-(1,1-bis{4-[2-diazo-1(2H)naphthalene-5-sulfonyloxy]-phenyl}ethyl)-4-(1-{4-[2-diazo-1(2H)naphthalene-5-sulfonyloxy]phenyl}methylethyl) benzene (S-DNQ) as a photosensitive compound has been developed. PDHN (number-average molecular weight: 13,000; polydispersity index: 1.9) was prepared by oxidative coupling polymerization of the 2,6-dihydroxynaphthalene-benzylamine complex using iron(III) chloride hexahydrate in the solid state. A 10 wt % loss temperature of PDHN was 450 degreesC in air, and the film of 1 mum thickness showed excellent transparency above 400 nm. The resist system consisting of PDHN and S-DNQ gave a clear positive pattern when it was exposed to 436 nm of light, followed by development with a 0.50 wt % aqueous tetramethylammonium hydroxide solution at 25 degreesC. The sensitivity (D) and contrast (gamma) were 300 mJ/cm(2) and 2.1, respectively.