A method of manufacturing a multicore fiber preform including: a plurality of core portions; and a cladding portion surrounding outer peripheries of the plurality of core portions and having a lower refractive index than maximum refractive indices of the plurality of core portions, includes: a first process of inserting each of core preforms each including one of the core portions into each of holes arranged in a longitudinal direction in a central cladding preform, the central cladding preform having a rod-shape and being configured to form a part of the cladding portion; a second process of integrating the central cladding preform and the core preforms; and a third process of arranging an outer cladding portion configured to form a part of the cladding portion on an outer periphery of the central cladding preform.