A plastic ferrule including a centering section having a tubular body. The tubular body is provided with an outer-circumferential centering reference surface and a center axis of the centering reference surface. The centering section includes a resinous outer tube part having the outer-circumferential centering reference surface and provided, along the center axis, with a coated-fiber holding bore for securely accommodating a coated optical fiber and a fixing bore extending from the coated-fiber holding bore, the outer tube part forming a tubular wall with a generally uniform thickness as a whole. The centering section also includes an inner tube part fixed to the fixing bore of the outer tube part and provided along the center axis with an uncoated-fiber holding bore, communicating with the coated-fiber holding bore, for securely accommodating an uncoated optical fiber.