To provide a lightweight small diameter tube having high tenacity and high precision appropriate for tubes for various precision instruments, such as a tube for inserting minute amount of liquid, a treatment instrument inserting a channel for an endoscope, a guide tube for an endoscope or a catheter, or the like.

This high tenacity tube comprises a tube A having an outer diameter of 0.3-10 mm and a wall thickness of 0.01-3 mm reinforced by high tenacity fibers B around its outer periphery. The high tenacity fiber is a composite fiber comprising a core component of a meltable liquid crystal polymer and a sheath component of a flexible polymer, and has a fiber diameter of 5-100 μm, a fiber strength of 8 cN/dtex or more and an elasticity of 250 cN/dtex or more.