Provided are an organic silicon compound of the following formula (I): ##STR00001## (wherein, R.sub.1 to R.sub.20 represent each independently alkyl, alkoxy, aryloxy, cycloalkyl, alkylcycloalkyl, aryl, dialkylamino or the like, and the aryloxy and aryl may be substituted with a substituent selected from the group consisting of alkyl, alkoxy and alkoxyalkyl.) which can be used for suppression of coloration and thermal deterioration of an organic material in molding, and an organic material composition containing the organic silicon compound and a method of producing the organic silicon compound.