In order to clarify the effects of vacuum on the strength and the time-dependent deformation of Ti nanocolumns, we conducted monotonically-increasing-loading and creep experiments using micro-specimens in laboratory air and vacuum environments. In the monotonically-increasing-loading experiments, critical apparent shear stress, defined as the critical force divided by specimen area, in vacuum environment was larger than that in air environment. The result indicated that an environment significantly influenced the strength. In the creep experiments, the Ti nanocolumns showed time-dependent deformation in both air and vacuum environments. The steady-state creep rate in air environment was much higher than that in vacuum environment. The results suggested that the time-dependent deformation in the nanocolumns was significantly accelerated by air or moisture environment.