An electromagnetic device and a method for manufacturing the same are disclosed. The electromagnetic device includes a base plate, a magnetic core, multiple transmission units, and connection layers. The base plate includes a central part defining multiple inner via holes and a peripheral part defining multiple outer via holes. An annular accommodating groove is defined between the central part and the peripheral part. The magnetic core is received in the annular accommodating groove. Transmission units are located on both sides of the base plate. Each transmission unit includes a transmission wire layer including multiple conductive wire patterns, and each conductive wire pattern bridges one inner via hole and one outer via hole. Each of the connection layers is set on one side of the transmission wire layer close to the base plate. At least one connection layer has a dielectric loss no larger than 0.02.