Reactor, converter, and power conversion device

A reactor, comprising:

• a coil:
• and
• a magnetic core,
• the coil including one winding portion,
• the magnetic core including a middle core part, two side core parts and two end core parts,
• the middle core part having a part to be arranged inside the winding portion,
• each of the two side core parts being arranged side by side with the middle core part outside the winding portion,
• each of the two end core parts being arranged to connect the middle core part and the two side core parts outside end parts of the winding portions,
• the magnetic core having a first region and a second region having a higher relative magnetic permeability than the first region,
• the first region including two corner parts constituted by the middle core part and each of the two end core parts,
• the second region including a base end region and a projecting region,
• the base end region extending in a parallel direction of the middle core part and the two side core parts across an axis of the middle core part in each of the two end core parts, and
• the projecting region projecting toward the middle core part from the base end region.