In this letter, we consider a secrecy wireless powered communication network (WPCN), where an information source sends message to a legitimate destination with the energy harvested from a power source, while an eavesdropper intends to intercept the information. In such a secrecy WPCN, transmit power and transfer time at the power source, and spatial beam at the information source, are interrelated, and together affect the secrecy performance. Considering imperfect channel state information about the eavesdropper channel, a robust resource allocation scheme is proposed for maximizing the secrecy rate in the worst case. Finally, the simulation results validate the effectiveness of the proposed scheme.