Provided is a rotary machine in which the output of a magnetic sensor is hardly lowered even if the rotation speed of a rotor becomes high. The rotary machine includes a rotor, a housing, a magnet, and a magnetic sensor. The rotor axially rotates around a rotation axis. The housing is formed of a conductive material and contains the rotor. The magnet is attached to the rotor such that an arrangement direction of a pair of magnetic poles is in a radial direction of the rotor. The magnetic sensor is attached to the housing. The magnetic sensor detects a time variation of a magnetic field generated from the magnet to detect the rotation speed of the rotor. The magnetic sensor is located on the outside than the magnet in the radial direction. The magnetism sensing direction of the magnetic sensor is orthogonal to the radial direction.