A warning device for a vehicle comprising: an electric motor that applies steering assisting force to a steered mechanism of a vehicle; a torque detector that detects a steering torque; a phase compensator that executes phase compensation on the steering torque detected by the torque detector; a basic assist current value setting unit that sets a basic assist current value (Io*), based on a phase-compensated torque that is a steering torque the phase of which is compensated by the phase compensator; a vibration wave generator that generates a warning vibration wave (le) having a prescribed frequency based on an operating state of the vehicle; a target current value computing unit that computes a target current value (I*) for the electric motor by adding the warning vibration wave (le) generated by the vibration wave generator to the basic assist current value (Io*) set by the basic assist current value setting unit; and a motor controller that controls the electric motor based on the target current value (I*) computed by the target current value computing unit, wherein the phase compensator includes a characteristic switching unit that switches a frequency characteristic between a normal state where the warning vibration wave (le) is not generated by the vibration wave generator and a warning vibration wave (le) generated state where the warning vibration wave (le) is generated by the vibration wave generator, and the characteristic switching unit is configured to switch the frequency characteristic such that, in the warning vibration wave (le) generated state, a gain with respect to a prescribed frequency of the warning vibration (le) wave is smaller than a gain with respect to the prescribed frequency in the normal state, and a phase delay with respect to the prescribed frequency is smaller than a phase delay with respect to the prescribed frequency in the normal state. an electric motor that applies steering assisting force to a steered mechanism of a vehicle; a torque detector that detects a steering torque; a phase compensator that executes phase compensation on the steering torque detected by the torque detector; a basic assist current value setting unit that sets a basic assist current value (Io*), based on a phase-compensated torque that is a steering torque the phase of which is compensated by the phase compensator; a vibration wave generator that generates a warning vibration wave (le) having a prescribed frequency based on an operating state of the vehicle; a target current value computing unit that computes a target current value (I*) for the electric motor by adding the warning vibration wave (le) generated by the vibration wave generator to the basic assist current value (Io*) set by the basic assist current value setting unit; and a motor controller that controls the electric motor based on the target current value (I*) computed by the target current value computing unit, wherein the phase compensator includes a characteristic switching unit that switches a frequency characteristic between a normal state where the warning vibration wave (le) is not generated by the vibration wave generator and a warning vibration wave (le) generated state where the warning vibration wave (le) is generated by the vibration wave generator, and the characteristic switching unit is configured to switch the frequency characteristic such that, in the warning vibration wave (le) generated state, a gain with respect to a prescribed frequency of the warning vibration (le) wave is smaller than a gain with respect to the prescribed frequency in the normal state, and a phase delay with respect to the prescribed frequency is smaller than a phase delay with respect to the prescribed frequency in the normal state.