We demonstrate inline holography with a soft-x-ray vortex beam having an orbital angular momentum. A hologram is recorded as an interference pattern between a Bragg-diffracted wave from a fork grating and a divergent wave generated by a Fresnel zone plate. The images obtained exhibit fork-shaped interference fringes, which confirm the formation of a vortex beam. By analyzing the interference images, we successfully obtain a spiral phase distribution with a topological charge =±1. The results demonstrate that the inline-holography technique may be an effective probe for the characterization of topological defects in magnetic textures.