In this paper the following free boundary problem
{utt-∂x(ux/√1+ux2)=0, in{(t, x)|t>0, x>-l0}∩{u>0},
1/2ut2+1/√1+ux2-1+Q=0, in{(t, x)|t>0, x>-l0}∩∂{u>0}
is considered. The problem describes the peeling phenomenon. Different from the problem studied by K. Kikuchi and S. Omata, the nonlinear effects in the vibrating string is also considered. Under some reasonable assumptions, the local existence and uniqueness of classical solution for the free boundary problem is proved.