Anomalous Wtb Coupling in ep Collision

The potential of ep collision to prospect for anomalous Wtb vertex is discussed from the single top quark production process $ep\to t\bar{\nu }+X$ for TESLA+HERAp and CLIC+LHC energies. Sensitivities to anomalous couplings $F_{2L}$ and $F_{2R}$, in the case of CLIC+LHC, are shown to be comparable with LHC.