An electronic device has a primary coil 10; a secondary coil 20 disposed to face the primary coil 10; a coil sealing part 50 sealing the primary coil 10 and the secondary coil 20 and being made of sealing resin; a primary-side electronic element 110 electrically connected to the primary coil 10; and a secondary-side electronic element 210 electrically connected to the secondary coil 20. The primary-side electronic element 110 is provided on a primary-side extension part 60 extending from the primary coil 10 to an outside of the coil sealing part 50, or the secondary-side electronic element 210 is provided on a secondary-side extension part 70 extending from the secondary coil 20 to an outside of the coil sealing part 50.