A synchronous machine control means is provided with a magnet state output means (7) that estimates the magnetic flux of a permanent magnet forming the magnetic field of a synchronous machine (1); in a magnet state correction value calculation mode, the magnet state output means (7) calculates a magnet state correction value (Δφm1); in a magnet state estimation mode, the magnet state output means (7) is provided with a magnet stated estimation device (8) that calculates a magnetic flux estimation value (φm1′) of the permanent magnet under the given condition of a magnetic flux command (φ1) and a δ-axis current command (i1) and a magnet state correction means (9) that corrects the magnetic flux estimation value (φm1′) of the permanent magnet obtained by the magnet stated estimation device (8), by use of the magnet state correction value (Δφm1).