We present the results of a statistical study of brightness variability for 693 stars of the Pulkovo spectrophotometric database in five spectral bands in the range λλ 320–1080 nm. Significant brightness variations were detected in at least one spectral band against the background of the random noise for one-third of the stars not earlier believed to be variable. A comparison of the distributions of these variations in amplitude and spectral band for the normal and variable stars shows that variability is inherent to most stars to some extent and is often wavelength dependent.