PURPOSE: To provide an underground composite resin tube having light weight, flexibility, high strength against pressure, and freedom from a partial fracture.

CONSTITUTION: The first reinforcement strip 2 having the same sectional area of corrugation as a wall tube corrugation is embedded in a tube wall 1 comprising a spirally corrugated synthetic resin with a posture open downward over the range of the crest section 1a of the tube wall 1 and both side wall sections 1b and 1b continuous thereto. At the same time, the second reinforcement strip 2' is embedded with a posture open upward over the range of each trough section 1c of the tube wall 1 and both side wall sections 1b and 1b continuous thereto. Furthermore, both side plate sections 2b and 2b of the first reinforcement strip 2 are jointed to both side plate sections 2b' and 2b' of the second reinforcement strip 2' via polymerization at both side wall sections 1b and 1b of the tube wall 1.