To clarify the effects of internal disturbances in a liquid jet on the disintegration process, characteristics of water jet injected from the co-axial dual nozzle were experimentally investigated. Anomalous velocity profiles (deformed from the Poiseuille flow) at the nozzle exit were produced by the co-axial dual nozzle. Using a stroboscope and a camera, instability waves on the jet surface and the disintegration process of jet have been visualized. The breakup length, breakup width and spray width of jet were measured under various conditions of the air velocity and the internal velocity profile. As the results, influence of internal velocity profile on the surface wave formation and disintegration process can be seen.