An object of the present invention is to provide a method for efficiently producing an α-olefin low polymer at a high α-olefin low polymer selectivity and a high α-olefin low polymer yield with suppressing the deterioration of catalytic activity with time, and the invention relates to a method for producing an α-olefin low polymer, which comprises performing a low polymerization reaction of an α-olefin in the presence of a catalyst containing a chlorine atom-containing compound (d) and a reaction solvent, wherein the chlorine atom-containing compound (d) that are at least two compounds having specific chlorine atom elimination rate is supplied in predetermined ratio.