A position detection unit includes a magnetic sensor and a first magnetic field generator. The first magnetic field generator is spaced from and opposed to the magnetic sensor in a first-axis direction, includes a first multipolar magnet, and generates a first magnetic field to be exerted on the magnetic sensor. The first multipolar magnet includes N and S poles adjacent to each other along a plane orthogonal to the first-axis direction. The magnetic sensor and the first magnetic field generator are relatively movable with respect to each other along a second-axis direction orthogonal to the first-axis direction. A center position of the magnetic sensor in a third-axis direction orthogonal to both of the first-axis direction and the second-axis direction is different from a position in the third-axis direction of an interface between the N and S poles adjacent to each other in the third-axis direction.