Apparatus having magnetic fluid heat transport system

An image pickup apparatus comprising:

• an image sensor as a heating portion;
• a cooling portion,
• a conduit configured to circulate magnetic fluid having temperature sensitivity between the image sensor and the cooling portion;
• a magnetic field generator disposed on an object side in an optical axis direction further than the conduit and configured to apply a magnetic field to the magnetic fluid;
• and,
• wherein the conduit includes a first conduit area in which the magnetic fluid receives heat from the image sensor, a second conduit area from the first conduit area to the cooling portion, a third conduit area in which the magnetic fluid is cooled by the cooling portion, and a fourth conduit area from the cooling portion to the image sensor,
• wherein, when the image pickup apparatus is viewed from a back side in the optical axis direction, the magnetic field generator is disposed between the first conduit area and the third conduit area, and
• wherein a conduit volume inside the first conduit area is larger than that inside any of the second, third and fourth conduit areas.