An object of the present invention is to provide a silicon oligomer having a novel function that has not been achieved by a conventional condensation product of water and a tetraalkoxysilane. Provided are a silicon oligomer represented by the following formula (I) and a production method therefor: wherein R1 to R10 each independently is an alkyl group or a hydroxyalkyl group, each having 1 to 4 carbon atoms; X1 to X3 each independently is a group represented by the following formula (II); n is 0 or 1; and m is an integer of 1 to 3 when n is 0, and m is 1 when n is 1: wherein A is an alkylene group having 2 to 4 carbon atoms which may be branched, and 1 is an integer of 1 to 3.