Method for manufacturing multicore optical fiber

A method for manufacturing a multicore optical fiber, the method comprising:

• a step of forming a plurality of ring-shaped closed-end holes to extend from a first end toward a second end in an axial direction of a glass rod;
• a step of heating bottom parts of the plurality of ring-shaped closed-end holes and softening a plurality of center rods that each are surrounded by a corresponding one of the plurality of ring-shaped closed-end holes;
• a step of pulling out the plurality of center rods toward a side of the first end, forming a plurality of columnar closed-end holes from the plurality of ring-shaped closed-end holes, and treating the glass rod as a cladding material;
• a connecting step of connecting a supporting pipe to the first end of the cladding material;
• an inserting step of inserting core rods into the plurality of columnar closed-end holes in a one-to-one correspondence after the connecting step;
• and
• a drawing step of drawing the cladding material and the core rods while heating a portion near the second end of the cladding material and integrating the cladding material and the core rods after the inserting step.