Provided is a steel strip stabilizing apparatus which allows shape correction and vibration suppression in a steel strip, particularly, plated steel strip, in a non-contact manner. The steel strip stabilizing apparatus includes an apparatus support body disposed on at least one side of a traveling steel strip and a steel strip stabilizing unit comprising a magnetic field generating pole disposed on the apparatus support body to face the steel strip and a pole expansion part configured to provide steel strip attraction force to a steel strip-side end of the magnetic field generating pole so as to allow shape correction or vibration suppression in the steel strip. The present invention increases the (electro)magnetic attraction force on the plated steel strip that passes through a plating bath, and thereby effectively ensures shape (curvature) correction or vibration suppression (damping) in the plated steel strip and prevents plating variations in the steel strip, and ultimately makes it possible to improve the quality of the plating of the steel strip.