The effects of delay of visual feedback on two kinds of sensorimotor tasks were investigated. On the reciprocal tapping task, accuracy of performance decreased for 200, 500, and 767 msec. delay. The number of errors for the 1000-msec. delay is smaller than those for the other three conditions of delay. On the hand-writing task of both Kanji letters and English words, performance showed a large decrement with increasing delay. The most frequent kinds of error were the type of insertion of line elements or letter duplication. It was interesting that the size of written letters increased with lengthening delays of visual feedback.