The spectrophotometric variability of the classical magnetic CP star \alpha ^ { 2 } CVn in the ultraviolet spectral region from 1150 to 3200 Å is investigated .
This study is based on the archival International Ultraviolet Explorer data obtained at different phases of the rotational cycle .
The brightness of the star at spectral region from 3015 to 3138 Å is constant over the period of rotation which means that the so called ’ null wavelength region ’ exist on these wavelengths .
Moreover , the minima values of the amplitude of light curves are reached in the spectral region at \lambda \lambda 1660 and 1900 Å .
The monochromatic light curves in the ’ pseudo-continuum ’ of this star change their shape with wavelength .
All light curves with \lambda \leq 2505 Å have a similar shape , but the monochromatic light curves with \lambda > 2505 Å shows the phase displacement of the minimum from 0.0 at \lambda 2505 Å to 0.3 at \lambda 2993 Å .

Key words : stars : chemically peculiar – stars : individual : \alpha ^ { 2 } CVn – stars : variables : other .