NOVELTY - A positive photosensitive siloxane composition contains polysiloxane (Ia), polysiloxane (Ib), diazonaphthoquinone derivative and solvent. The polysiloxane (Ia) is obtained by hydrolyzing and condensing silane compound (I) and silane compound (II) in presence of a basic catalyst. The polysiloxane (Ib) is obtained by hydrolyzing and condensing silane compound (I) in presence of an acid or basic catalyst.    USE - Positive photosensitive siloxane composition is used for forming cured film (claimed) e.g. planarizing film for thin film transistor, liquid crystal display element and organic electroluminescent element, and interlayer insulation film for semiconductor element, solid-state image sensor, reflection-preventing board, optical filter, high intensity light emitting diode, touch panel, solar cell and optical waveguide.    ADVANTAGE - The film formed using the composition has high sensitivity, heat resistance, transparency, and resolution.    DETAILED DESCRIPTION - A positive photosensitive siloxane composition contains polysiloxane (Ia), polysiloxane (Ib), diazonaphthoquinone derivative and solvent. The polysiloxane (Ia) is obtained by hydrolyzing and condensing silane compound of formula: RSi(OR1)3 (I) and silane compound of formula: Si(OR1)4 (II) in presence of a basic catalyst. The polysiloxane (Ib) is obtained by hydrolyzing and condensing silane compound (I) in presence of an acid or basic catalyst. The pre-baked film formed using the composition has dissolution rate of 1000 Angstrom /second or less in 5 wt.% of tetramethylammonium hydroxide aqueous solution with respect to polysiloxane (Ia). The pre-baked film formed using the composition has dissolution rate of 100 Angstrom /second or more in 2.38 wt.% of tetramethylammonium hydroxide aqueous solution with respect to polysiloxane (Ib).    R=1-20C linear, branched with which arbitrary methylene optionally substituted by oxygen, cycloalkyl, or 6-20C aryl in which arbitrary hydrogen is optionally substituted by fluoro;and    R1=1-5C alkyl.