The present invention relates to a field coil assembly of an electromagnetic clutch for a compressor. The present invention comprises a core 210, and a coil 240 installed to the core 210 and formed by winding a unit wire 250. At this time, the unit wire 250 wound on the coil 240 is made of aluminum, and an area ratio R of an inner sectional area M of the core 210 to a cross-sectional area of the unit wire 250 is 400 to 640. According to the present invention as above, since the unit wire 250 used for the coil 240 is made of aluminum with a small specific weight and low price rather than copper, the weight of the field coil assembly 200 is decreased to improve fuel efficiency of a vehicle and decrease a production cost of the field coil assembly 200.