A coil apparatus having a divided winding conformation and a manufacturing method of the coil apparatus which can prevent a winding from collapsing while achieving a reduction in size of a core and simplification of a structure. A coil apparatus includes a ferrite core and a coil provided around the core. The coil includes at least a first coil portion and a second coil portion, and a boundary end surface of the first coil portion on the second coil portion side is inclined in such a manner that its inner peripheral side is closer to the second coil portion than its outer peripheral side. Further, a boundary end surface of the second coil portion on the first coil portion side is inclined in such a manner that its outer peripheral side is closer to the first coil portion than its inner peripheral side.