Abstract: A three-axis vibration acceleration pickup with the handle of a vibration-generating tool such as, an angle grinder or the like, feeds detected vibrations along the three axes to an A/D converter 19. A microcomputer processes the digitized data to feed a display portion. Each time continuous operation of the tool is interrupted, an 8-hour equivalent acceleration value is obtained based on the detected vibration acceleration signal. The result is added to previous acceleration values so as to accumulatively add up the total value in one day. Each time continuous operation is interrupted, a frequency load vibration acceleration value is obtained, and an 8-hour equivalent acceleration value is obtained based on this. A residual surplus time is obtained and displayed by using the 8-hour equivalent acceleration value.