An external-control type fan clutch device, comprising: a torque transmission chamber incorporating a drive disk therein and provided in a sealed housing, the sealed housing being composed of a non-magnetic case and a cover mounted on the case and being supported via bearings (13/14/15) on a rotary shaft fixed with the drive disc; at least one oil circulating flow passage hole communicating with a torque transmission gap and provided on a side wall face of an oil reserving chamber, the oil reserving chamber being provided by making inside of the drive disk hollow; a magnetic valve member for opening and closing the oil circulating flow passage hole, the valve member having an armature attached to a leaf spring mounted on the drive disk; an electromagnet supported on the rotary shaft via a bearing (13/14/15); and a ring-like magnetic member arranged on an outer periphery of the rotary shaft via a ring-like non-magnetic member, wherein opening and closing of the oil circulating flow passage hole are controlled by the valve member actuated by the electromagnet, and a rotation torque transmission from a driving side to a driven side is controlled by increasing and decreasing an effective contact area of oil in the torque transmission gap formed between the driving side and the driven side, characterizec9 in that an oil supply chamber is provided in the annular oil reserving chamber, and the oil circulating flow passage hole and an oil recovery port are arranged in the oil supply chamber, the oil supply chamber being formed of a partition wall and a plate-like partition wall for shielding one end of the arc-like partition wall, the partition wall being composed of an arc-like wall concentric to the annular oil reserving chamber. a torque transmission chamber incorporating a drive disk therein and provided in a sealed housing, the sealed housing being composed of a non-magnetic case and a cover mounted on the case and being supported via bearings (13/14/15) on a rotary shaft fixed with the drive disc; at least one oil circulating flow passage hole communicating with a torque transmission gap and provided on a side wall face of an oil reserving chamber, the oil reserving chamber being provided by making inside of the drive disk hollow; a magnetic valve member for opening and closing the oil circulating flow passage hole, the valve member having an armature attached to a leaf spring mounted on the drive disk; an electromagnet supported on the rotary shaft via a bearing (13/14/15); and a ring-like magnetic member arranged on an outer periphery of the rotary shaft via a ring-like non-magnetic member, wherein opening and closing of the oil circulating flow passage hole are controlled by the valve member actuated by the electromagnet, and a rotation torque transmission from a driving side to a driven side is controlled by increasing and decreasing an effective contact area of oil in the torque transmission gap formed between the driving side and the driven side, characterizec9 in that an oil supply chamber is provided in the annular oil reserving chamber, and the oil circulating flow passage hole and an oil recovery port are arranged in the oil supply chamber, the oil supply chamber being formed of a partition wall and a plate-like partition wall for shielding one end of the arc-like partition wall, the partition wall being composed of an arc-like wall concentric to the annular oil reserving chamber.