In a steering apparatus, a differential lock mechanism has a lock holder in which a plurality of groove portions are formed on an outer periphery thereof, and selectively allows and prohibits to generate a difference of steering amount in the rotational direction between an input shaft and an output shaft by selectively engaging and disengaging an engaging portion with respect to the groove portions. A rotation sensor detects the position in the rotational direction of the lock holder during one rotation of the lock holder and repeatedly detects the same sensor pattern being output a plurality of times. A variable transfer ratio unit ECU detects which groove portion, from among the plurality of groove portions, the engaging portion is engaged with using the sensor pattern output by the rotation sensor when a side portion of one of the groove portions is pressing against a side portion of the engaging portion.