  In the present paper we explicitly construct the on-shell supersymmetric
component action for a 3-brane moving in D=8 within the nonlinear realizations
framework. Similarly to the previously considered case of the super 3-brane in
D=6, all ingredients entering the component action follow from the nonlinear
realizations approach. The component action of the 3-brane possesses N=4, d=4
supersymmetry partially broken to N=2, d=4 one. The basic Goldstone superfield
is the generalized version of N=2,d=4 hypermultiplet. The action has a
structure, such that all terms of higher orders in the fermions are hidden
inside the covariant derivatives and vielbeins. The main part of the component
action mimics its bosonic cousin in which the ordinary space-time derivatives
and the bosonic worldvolume are replaced by their covariant (with respect to
broken supersymmetry) supersymmetric analogs. The spontaneously broken
supersymmetry fixes the Ansatz for the component action, up to two constant
parameters. The role of the unbroken supersymmetry is just to fix these
parameters.
