By using the second harmonic generation (SHG) microscope, which we have recently developed, two‐dimensional images of ferroelectric domain structure were successfully obtained by exploiting the inhomogeneous distribution of the quadratic nonlinear optical constant in specimens. 90° domain structure ofBaTiO3was observed with intensity contrast of the second harmonic wave. A periodically inverted antiparallel domain inLiTaO3was also observed. This fact indicates that the SHG microscope provides a new method of observing antiparallel ferroelectric domain structure in a nondestructive way, which is especially important for characterizing the quasiphase matched devices for compact blue light lasers. ©1995 American Institute of Physics.