A vehicle steering device comprising: two motors (17, 18) each configured to generate a drive force that steers a steerable wheel of a vehicle; and two controllers (41, 42) respectively corresponding to the two motors (17, 18), each of the two controllers (41, 42) being configured to individually control a corresponding one of the motors (17, 18), wherein one of the two controllers (41, 42) is a first controller and the other one of the two controllers (41, 42) is a second controller, the first controller is configured to calculate a command value corresponding to a total torque that should be generated in the two motors (17, 18), the command value is divided into individual command values using a changeable distribution ratio (DR 1, DR 2) set for each of the motors (17, 18), the individual command values respectively corresponding to the motors (17, 18), and the two controllers (41, 42) are configured to respectively supply the motors (17, 18) with current corresponding to the individual command values, characterized by comprising: a steering rod configured to steer the steerable wheel; and two transmission mechanisms each configured to individually transmit the drive force of a corresponding one of the two motors (17, 18) to the steering rod, wherein when an execution condition that has been preset for an anomaly detection process is satisfied, the first controller is configured to: set the distribution ratios (DR 1, DR 2) of the command value to an uneven distribution ratio; interchange the set distribution ratios (DR 1, DR 2) between the two motors (17, 18); and detect an anomalous increase in friction of the transmission mechanisms by comparing a total value of current in the two motors (17, 18) prior to interchanging the distribution ratios (DR 1, DR 2) with a total value of current in the two motors (17, 18) subsequent to interchanging the distribution ratios (DR 1, DR 2). two motors (17, 18) each configured to generate a drive force that steers a steerable wheel of a vehicle; and two controllers (41, 42) respectively corresponding to the two motors (17, 18), each of the two controllers (41, 42) being configured to individually control a corresponding one of the motors (17, 18), wherein one of the two controllers (41, 42) is a first controller and the other one of the two controllers (41, 42) is a second controller, the first controller is configured to calculate a command value corresponding to a total torque that should be generated in the two motors (17, 18), the command value is divided into individual command values using a changeable distribution ratio (DR 1, DR 2) set for each of the motors (17, 18), the individual command values respectively corresponding to the motors (17, 18), and the two controllers (41, 42) are configured to respectively supply the motors (17, 18) with current corresponding to the individual command values, characterized by comprising: a steering rod configured to steer the steerable wheel; and two transmission mechanisms each configured to individually transmit the drive force of a corresponding one of the two motors (17, 18) to the steering rod, wherein when an execution condition that has been preset for an anomaly detection process is satisfied, the first controller is configured to: set the distribution ratios (DR 1, DR 2) of the command value to an uneven distribution ratio; interchange the set distribution ratios (DR 1, DR 2) between the two motors (17, 18); and detect an anomalous increase in friction of the transmission mechanisms by comparing a total value of current in the two motors (17, 18) prior to interchanging the distribution ratios (DR 1, DR 2) with a total value of current in the two motors (17, 18) subsequent to interchanging the distribution ratios (DR 1, DR 2). a steering rod configured to steer the steerable wheel; and two transmission mechanisms each configured to individually transmit the drive force of a corresponding one of the two motors (17, 18) to the steering rod, wherein when an execution condition that has been preset for an anomaly detection process is satisfied, the first controller is configured to: set the distribution ratios (DR 1, DR 2) of the command value to an uneven distribution ratio; interchange the set distribution ratios (DR 1, DR 2) between the two motors (17, 18); and detect an anomalous increase in friction of the transmission mechanisms by comparing a total value of current in the two motors (17, 18) prior to interchanging the distribution ratios (DR 1, DR 2) with a total value of current in the two motors (17, 18) subsequent to interchanging the distribution ratios (DR 1, DR 2). set the distribution ratios (DR 1, DR 2) of the command value to an uneven distribution ratio; interchange the set distribution ratios (DR 1, DR 2) between the two motors (17, 18); and detect an anomalous increase in friction of the transmission mechanisms by comparing a total value of current in the two motors (17, 18) prior to interchanging the distribution ratios (DR 1, DR 2) with a total value of current in the two motors (17, 18) subsequent to interchanging the distribution ratios (DR 1, DR 2).