PURPOSE: To obtain a polysilane, having a uniform molecular weight and controlled sequence of substituent groups and useful as a functional polymer such as a nonlinear optical material or an electrically conductive polymer.

CONSTITUTION: This polysilane is expressed by formula I (R1 to R2 are H, an alkyl, aryl, etc.). For example, 2,2,3,3,4,4,5,5-octaethyl-1,1,6,6-tetramethyl-1,6- diphenylhexasilane is cited as the polysilane. Furthermore, the polysilane is obtained by reacting a small-membered ring polysilane expressed by formula II (e.g. hexapropylcyclotrisilane) with an organolithium reactional agent expressed by the formula R9-Li (R9 is H, silyl, etc.) (e.g. phenyldimethylsilyl- lithium) and then reacting the resultant product with silanes expressed by formula III (X is releasable group) (e.g. phenyldimethylchlorosilane). The reaction is preferably carried out at -78°C to ambient temperature.