One of the purposes of the present invention is to provide a silicone compound which has a specific number of silicon atoms, is well compatible with (meth)acryl monomers, is suitable as an ophthalmic monomer and provides a polymer having excellent durability of mechanical strength in a buffered phosphate solution. Another purpose of the present invention is to provide a silicone compound which functions well as a crosslinking agent for a polymerizable monomer. Further, another purpose is to provide a method for preparing the silicone compound, in particular the silicone compound having one specific structure at a high ratio. In the first aspect, the present invention provides a compound represented by the following formula (1-1): and a method for preparing the silicone compound. In the second aspect, the present invention provides a compound represented by the following formula (2-1): and a method for preparing the silicone compound.