Inversion domains with a V-shape were found to nucleate inside a Mg-doped InN heteroepitaxial layer. They resemble Al-polarity domains, observed recently, in N-polarity AlN films. However, the angle between the side-walls of the V-shaped domain and the c-axis differs in these two cases. In InN, this angle is almost two times bigger than that reported for AlN. The origin of V-shaped inversion domains in InN film is not yet clear.