  In this paper, we study on three kinds of spacelike helicoidal surfaces in
Minkowski $4$--space. First, we give an isometry between such helicoidal
surfaces and rotational surfaces which is a kind of generalization of Bour
theorem in Minkowski $3$--space to Minkowski $4$--space. Then, we investigate
geometric properties for such isometric surfaces having same Gauss map. By
using these results, we give the parametrizations of isometric pair of
surfaces. As a particular case, we examine the right helicoidal surfaces in
view of Bour's theorem. Also, we present some examples by choosing the
components of the profile curves and the parameters of the surfaces via
Mathematica.
