PURPOSE: To increase the bending strength, tensile strength, and pressure resistance of a hose by strengthening the bonding of the side edges of the hose by a method in which when a hose body molded under unvulcanized condition is vulcanized, a slight resistance is applied in the advancing direction of the hose.

CONSTITUTION: When a rubber tape 6 at the center of which a hard synthetic resin 5 is buried is positioned between a forming roll group 2 and a pushing roll 3, the side edges are bonded with each other while being sent out in a spiral form, and a hose body is formed and advanced to the tip of the forming roll group 2 while being turned. The hose body separated while being advanced goes forward while being supported by a free rotary roll 9 at its upper end and heated from outside. Since the hose body is suported by the free rotary roll 9 when it comes out of the forming roll group 2, a slight resistance is applied to the rotation of the hose, and thereby the side edges of the tape 6 are pushed from the back side and pressing contacted with each other. They are then heated from inside and outside and integrated with sufficient strength upon vulcanization.