Coil unit, power transmission device, and power reception device

A power reception device that receives electric power from a power transmission device in a contactless manner, the power reception device comprising:

• ferrite cores each of which is in a form of a plate;
• and
• a coil that is disposed to face the ferrite cores, the coil surrounding an area around a winding axis extending in a thickness direction of each of the ferrite cores, and the coil including a plurality of curve portions, wherein each of the plurality of curve portions of the coil is wound across a virtual straight line extending through a curvature center of the curve portion, the ferrite cores include curve portion ferrite cores that are disposed to face the plurality of the curve portions, respectively, and each of the curve portion ferrite cores is provided such that a width of a region with a highest magnetic flux density is larger than a width of a region other than the region with the highest magnetic flux density, in a region that faces the coil, in a case where a length direction is defined as a direction in which the virtual straight line extends, and a width direction is defined as a direction perpendicular to the virtual straight line.