Dynamic wall motion in a (100)  4% Si-Fe single crystal picture frame has been systematically studied by the Kerr magneto-optical method over a wide frequency range (from 30 to 5 kHz) driving field. The following results were noted: i) An increase in number of domain walls during the movement, a drift of oscillating walls, and also wall bowing were observed. ii) Unusual hysteresis loops were observed as walls merged which can be explained through an interaction between walls. iii) The frequency dependence of the permeability and loss in the initial permeability region is determined essentially through the behavior of isolated walls. Neither a complete flexible wall model nor a planar wall model can explain these results and the effect of wall tension or the change in spin structure of a moving wall must be taken into account.