PROBLEM TO BE SOLVED: To provide a raw material for forming a thin film excellent in thermal stability, reactivity with reactive gas and step coverage property and capable of being applied to an ALD method, and to provide a raw material for forming a thin film capable of providing the thin film having the content of phosphorus of 10 to 20 mass%.SOLUTION: A raw material for forming a thin film has a silicon compound represented by the general formula (1). In the formula (1), Rto Rrepresent each independently an alkyl group having 1 to 4 carbon atoms and X represents a monovalent organic residue having a phosphorus element.
