Light-driven swimming particles hold great potential in wide applications ranging from next-generation drug delivery to versatile microrobotic devices. It is desired that the self-propelled microparticles should swim not only autonomously but also directionally to achieve their goals in their potential applications. This paper presents the first example of fully organic colloidal particles of a spiropyran-terminated hyperbranched polymer that can be driven and meanwhile steered by a UV light source, swimming straight towards the UV source. The mean-square velocities of the photochromic suspension particles are about 20 mu m s(-1), and increase to about 54 mu m s(-1) with the addition of NaCl of 0.5%. The phototactic propulsion is supposed to be originated from the UV irradiation-induced interfacial tension gradient on the surface of the colloidal particles. This finding allows for the design of new microengines for next-generation drug delivery systems, microrobotic devices, and self-adaptive photocatalysts, etc.