The phase of the scattered far-field from flaws is focused and the phase shift analysis is carried out to quantify the scattered waveforms. The basic tool of the phase shift analysis is the integral representation of the scattered wave field. The scattering amplitude of the scattered far-field is first defined. The phase shift of the scattered far-field is then introduced by expanding the scattered far-field into partial waves with spherical wave components and taking into account the energy relation. The phase shift introduced represents the shift of phase in the scattered wave from the phase in an incident wave. The far-field integral representation for the scattered field is utilized to derive the explicit expression of the phase shift, and the integral representation of the phase shift is obtained as a surface integral over the flaw. This integral representation is true for arbitrary flaw shape and it relates to the flaw geometry and the boundary conditions on the flaw surface. The boundary element method is adopted for the determination of boundary quantities on the flaw surface. As an application of the phase shifts in the scattered far-field, a flaw shape is reconstructed from the information on the phase shifts.