Topological insulators have been studied extensively owing to its distinguished characteristics, which generates the edge state in which wave can propagate without backscattering. This work proposes a phononic crystal with distorted hexagonal holes, as an elastic topological insulator for in-plane wave based on the analogues of valley hall effect. First, the existence of a nontrivial valley topological phase on the phononic crystal is revealed by Bloch wave functions, Bloch frequencies at the valley, and numerically calculated valley Chem numbers, respectively. Then, a topologically protected edge state is generated on the boundary of two phononic crystals with different topological phases. Its topological protection property is confirmed on the band diagram by a supercell method utilizing the revealed valley topological phases. Finally, the nature of the edge state, which is topologically protected against sharp angles, is observed directly through a full field simulation.