To provide a manufacturing method for a helical antenna wherein the molding can be performed by a die with a simple structure, the appearance is excellent, the manufacturing cost is suppressed, and also, the manufacturing work is simplified.

A helical coil 10 is fitted in a primary cavity of a primary molding die, and a primary sliding core is inserted in the inner periphery of the distal end section of the helical coil 10 by a length portion which is determined by a specified ratio to the length of the helical coil 10. Then, a resin is filled in the primary cavity, and a primary molded article 30 having a recess section 31 of a specified depth on the distal end section is molded. The primary molded article 30 is fitted in a secondary cavity 51 of a secondary molding die 50, and a secondary sliding core 55 is inserted in the recess section 31 which is formed on the distal end section of the primary molded article 30 through a secondary through hole 54 which is formed on the secondary molding die 50. Then, the filling of the resin to the secondary cavity 51 is started. After the completion of the filling of the resin, the secondary sliding core 55 is pulled out from the recess section 31, and a secondary molded article is molded by filling the resin in the recess section 31 as well.