A high-precision coordinate input apparatus having a small circuit construction. A vibrating pen transmits vibration onto a vibration transmitting tablet, then vibration sensors provided at corners of the vibration transmitting tablet detect the vibration. One of the vibration sensor is used as a reference sensor. Time difference between vibration detecting timing by this reference sensor and detecting timing by one of the other sensors is measured. This measurement is performed on all the vibration sensors with respect to the reference sensor. The obtained time differences are converted into distance differences for calculation of the coordinates of the position in which the vibration has been generated. The vibrating pen has a power source and it operates independent of the apparatus main body. The vibrating pen changes its frequency of vibration in accordance with the voltage of the power source. The apparatus main body captures this change in the vibration frequency and obtain the state of the vibration pen power source.