A magnetic device comprises a lead frame, a first core body and a coil. The lead frame has a first portion and a second portion spaced apart from the first portion. A first core body is disposed on the lead frame, wherein the first core body comprises a first through opening and a second through opening. A coil is disposed on the first core body, wherein the coil has a first terminal and a second terminal, wherein the first portion is electrically connected with the first terminal via the first through opening, and the second portion is electrically connected with the second terminal via the second through opening, respectively.