The object of the present invention is to provide an organosilicon compound having an oxetanyl group, which has a high proportion of an inorganic part in the structure, which, after production thereof, is stable with no gelling, and which has excellent storage stability when it is formed into a composition, and a production method thereof and a curable composition. The organosilicon compound is a compound having an oxetanyl group obtained by a method including a process in which a silicon compound A represented by the formula (1) and a silicon compound B having four siloxane bond-forming groups are subjected to hydrolysis and condensation at a ratio of 0.3 to 2.8 mol of silicon compound B based on 1 mol of silicon compound A. [In the formula, R0 is an organic group having an oxetanyl group, R1 is an alkyl group having 1 to 6 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an organic group having an oxetanyl group, X is a hydrolyzable group, and n is 0 or 1.]