Rod insertion jig and method for producing multicore optical fiber base material

A rod insertion jig configured to insert a glass rod into a hole penetrating a cladding preform, wherein

• the cladding preform is a columnar member having a first end and a second end facing each other, and includes a first hole that is the hole penetrating along a central axis of the cladding preform from the first end to the second end at a position deviated from the central axis in a section perpendicular to the central axis,
• a first glass pipe is connected to the first end of the cladding preform,
• a second glass pipe is connected to the second end of the cladding preform,
• a first glass rod that is the glass rod inserted into the first hole is a rod-shaped member of which an axial direction is a first direction,
• the rod insertion jig includes
• a support portion that is installed in contact with an inner surface of the first glass pipe,
• a first holding portion that is supported by the support portion inside the first glass pipe, and
• a first moving portion that is a member for moving the first glass rod,
• the first holding portion has a first mounting surface on which the first glass rod is mounted along the first direction,
• the support portion supports the first holding portion such that the first glass rod mounted on the first mounting surface entirely overlaps the first hole as viewed from the first direction, and
• the first moving portion moves the first glass rod mounted on the first mounting surface in the first direction.