Production method for multicore optical fiber

A production method for a multicore optical fiber, comprising:

• a preform forming step of forming a common cladding tube made of silica glass and having a plurality of holes extending in an axial direction between a first end and a second end;
• an end-face working step of digging the common cladding tube except for an outer peripheral portion from the second end toward the first end to a predetermined depth to form a third end;
• a connection step of connecting a glass tube to the second end;
• an insertion step of inserting core rods made of silica glass into the plurality of holes of the common cladding tube to the third end;
• a sealing step of sealing the plurality of holes at the first end;
• and
• a drawing step of spinning the multicore optical fiber while depressurizing insides of the plurality of holes through the glass tube and combining the common cladding tube and the core rods from the first end.