The invention provides a method of manufacturing an N-type silicon single crystal having a resistivity of 0.05 Ωcm or less and a crystal orientation of by a Czochralski method, including: bringing a seed crystal into contact with a melt doped with a dopant in a crucible; forming a cone while adjusting a taper angle θ such that a ratio of the total of individual lengths of areas each having a taper angle θ ranging from 25° to 45° to length L of a cone side surface is 20% or less, where θ being formed between a growth direction of the silicon single crystal and the cone side surface when the cone is seen in a diameter direction of the silicon single crystal; and successively forming a straight body. The method can inhibit the generation of dislocations during the cone formation without reducing the yield and productivity.