A velocity error signal generation method for controlling a velocity by comprising an actual velocity signal from an actual velocity generator with a command velocity signalfrom a command velocity generator includes removing a direct current component from the actual velocity signal, adding the direct current component of the command velocity signal to the alternating current component of the actual velocity signal, adding a minute voltage to the command velocity signal, subtracting the minute voltage from the command velocity signal, comparing a first signal obtained by adding the direct current component of the command velocity signal to the alternating current component of the actual velocity signal with a second signal obtained by adding the minute voltage to the command velocity signal, comparing the first signal with a thrid signal obtained by subtracting the minute voltage from the command velocity signal, and determining whether the actual velocity or the command velocity will be used an an input for generating a velocity error signal. In a velocity generating apparatus for realizing the method, when the difference between the actual and command velocity signals is outside a predetermined range, the actual velocity is regarded as being erroneously measured and is then replaced with the command velocity to detect a velocity error, thereby enhancing the reliability of a control system.