A vehicle steering device comprising: a steering member that is operated for steering; a left steering operation mechanism configured to turn a left steered wheel; a right steering operation mechanism configured to turn a right steered wheel, the steering member and the left steering operation mechanism being not mechanically coupled together, the steering member and the right steering operation mechanism being not mechanically coupled together, the left steering operation mechanism being driven by a left steering motor, and the right steering operation mechanism being driven by a right steering motor; a target steered angle setter configured to set a left target steered angle (δ L *) that is a target value of a steered angle of the left steered wheel and a right target steered angle (δ R *) that is a target value of a steered angle of the right steered wheel; a left-steered-angle acquisition device configured to acquire a left steered angle (δ L) that is the steered angle of the left steered wheel; a right-steered-angle acquisition device configured to acquire a right steered angle (δ R) that is the steered angle of the right steered wheel; a left motor controller configured to control the left steering motor so that a left-steered-angle deviation (Δδ L) that is a difference between the left steered angle (δ L) and the left target steered angle (δ L *) decreases; und a right motor controller configured to control the right steering motor so that a right-steered-angle deviation (Δδ R) that is a difference between the right steered angle (δ R) and the right target steered angle (δ R *) decreases; characterized by a determiner configured to determine that an abnormality has occurred when an absolute value of difference between the left-steered-angle deviation (Δδ L) and the right-steered-angle deviation (Δδ R) is equal to or larger than a first threshold. a steering member that is operated for steering; a left steering operation mechanism configured to turn a left steered wheel; a right steering operation mechanism configured to turn a right steered wheel, the steering member and the left steering operation mechanism being not mechanically coupled together, the steering member and the right steering operation mechanism being not mechanically coupled together, the left steering operation mechanism being driven by a left steering motor, and the right steering operation mechanism being driven by a right steering motor; a target steered angle setter configured to set a left target steered angle (δ L *) that is a target value of a steered angle of the left steered wheel and a right target steered angle (δ R *) that is a target value of a steered angle of the right steered wheel; a left-steered-angle acquisition device configured to acquire a left steered angle (δ L) that is the steered angle of the left steered wheel; a right-steered-angle acquisition device configured to acquire a right steered angle (δ R) that is the steered angle of the right steered wheel; a left motor controller configured to control the left steering motor so that a left-steered-angle deviation (Δδ L) that is a difference between the left steered angle (δ L) and the left target steered angle (δ L *) decreases; und a right motor controller configured to control the right steering motor so that a right-steered-angle deviation (Δδ R) that is a difference between the right steered angle (δ R) and the right target steered angle (δ R *) decreases; characterized by a determiner configured to determine that an abnormality has occurred when an absolute value of difference between the left-steered-angle deviation (Δδ L) and the right-steered-angle deviation (Δδ R) is equal to or larger than a first threshold.