PURPOSE: To form a resin layer with uniform thickness over the inner and outer peripheries of a reticulate pipe by a constitution wherein the amounts of resin, which passe per unit time through the first, second and third intermediate portions of an inner mold and the downstream portion of it, are made equal to each other.

CONSTITUTION: A device consists of an outer mold 2, in which a resin inlet passage is bored and at the rear part of which a support part 6 to be inserted with supporting rods 5 is provided, and an inner mold 4, which has recesses 12 to receive rollers 7 arranged at the tip of each supporting rod 5 and consists of an upperstream portion 9, intermediate portions 4a, 4b and 14 and a downstream portion 10. The outer diameter of the upperstream portion 9 is made slightly smaller than the diameter of a reticulate pipe 1. At the intermediate portions 4a and 4b, the depths of grooves 13 are gradually made deeper and the outer diameter of the grooves is made to be equal to the outer diameter of the upperstream portion 9. The outer diameter of the intermediate portion 14 is gradually increased from the bottom surface of the grooves 13 so as to continuously connect with the downstream portion 10. The outer diameter of the downstream portion 10 is set so as to allow the amount of resin flowing out of the intermediate portions 4a and 4b to uniformly distribute over the inner and outer peripheries of the reticulate pipe 1. Thus, the resin can surely be passed through the reticulate pipe 1 to its inner periphery side and at the same time the resin can be laminated to uniform thickness in the inner and outer peripheries of the reticulate pipe 1.