An oscillating potato digger for power tillers was designed and constructed to evaluate the effects of vibration on potato digging. Changing the levels of amplitude, frequency, and travel speed, 16 combinations of such parameters were tested in the potato field. The measured variables were harvesting loss and damage, and storing loss of the mechanically harvested potatoes. It was observed that the operation of the digger blade was good with amplitude of 12 mm, frequency of 9.67 Hz, and travel speed of 0.87 km/hr. Under these conditions the harvesting loss and damage were 3.18 % and 0.67 % that are very lower than those of 6.83 % and 9.83 % of traditional harvesting method. The operating efficiency of the experimental digger under optimum operating conditions was about 552 $m^2$ per hour which was about 20 times higher than 27.2 $m^2$ per man per hour of traditional harvest.