The question is addressed if there is a possibility of interplanetary magnetic field reaching the Venus surface by magnetic diffusion across the ionosphere. We present a model calculation and estimate the magnetic diffusion time at Venus, and find out that the typical diffusion time scale is in a range between 11 and 40 h, depending on the solar activity and the ionospheric magnetic field condition. Magnetic field can thus permeate Venus surface and even Venus interior when the solar wind is stationary (i.e., no magnetic field reversal) on the time scale of half-a-day to several days.