It is an object to provide a manufacturing method of a multicore fiber preform that improves the positioning accuracy of cores, reduces the degree of core being non-circular shape, and improves the flexibility in designing. In the manufacturing method of a multicore fiber preform, n pieces of first core rods in a cylindrical shape with a radius r1, a second core rod in a cylindrical shape with a radius R1, and a cladding in a cylindrical shape are prepared, points P11 to P1n are set at positions, distances of which are X11 to X1n, respectively, from a point a1 on straight lines dividing an end surface into n pieces to have an equal central angle, about the point a1 on the end surface of the cladding such that X1max-r1