Nowadays non collinear magnetism is a rapidly growing field in the state-of-the-art applied and academic research. One of such new object is helical magnet PtMnGa which was shown ferromagnet in previous studies. Our theoretical calculation shows that the distance between two Mn-Mn neighbors is too short to keep their spins parallel. To confirm it, we have grown polycrystal and single crystal. The crystal structure is hexagonal similar to previous study. However, the magnetization M(T) shows spin reorientation transition at small magnetic field. we performed neutron diffraction which shows that at 100 K, the structure is commensurate which becomes long range incommensurate antiferromagnetic at 4 K. Furthermore, we intend to resolve magnetic Hamiltonian of this complex magnetic system, so far unknown, by mapping out the magnetic excitations over a large part of the reciprocal space.