Novel organo-silicone compounds represented by the formula, ##STR1## wherein R is hydrogen, halogen or alkyl group, R.sup.1, R.sup.2 and R.sup.3 are alkyl group, alkoxy group, phenyl radical, substituted phenyl radical, alkylcarbonyloxy group, or trialkylsilyloxy group, respectively, R.sup.4 is hydrogen, alkyl or alkenyl grup, and m and n are an integer, respectively but those do not represent same integer of 2, when all of R.sup.1, R.sup.2 and R.sup.3 represents methyl radical, a process for the manufacture of the compounds, and an anti-tumor agent which comprises as an effective component, at least one of the compounds.