The temporal variation of the activity of intermediate and deep focus earthquakes for the period from 1904 to 1974 is investigated on the basis of a uniform body-wave magnitude scale. The mb scale has been traditionally used for intermediate and deep focus earthquakes. However, the period of seismic waves and the Q function used for the magnitude determination have changed as a function of time, so that uniform evaluation of the activity is difficult. In this study, we used a body-wave magnitude MB determined from the maximum amplitude of body waves recorded by broad-band or long-period instruments to investigate the temporal variation. For the period form 1904 to 1952, mB values were calculated from the unpublished material of Gutenberg and Richter. For 1953 to 1958, mB values were calculated from the amplitude and the period data in Gutenberg's unpublished file. For the period from 1959 to 1974, seismological bulletins from various stations were used to determine mB. Consistency between the values of mB calculated from these different sources was carefully checked. The temporal variation of the number of intermediate-deep events with mB?7 is remarkably similar to that of shallow earthquakes M8? 7. The temporal variation of the energy release in intermediate-deep earthquakes shows a maximum around 1910. The sum of the energy release curve of intermediate-deep and shallow earthquakes shows a good correlation with the amplitude of the Chandler wobble. The energy release becomes maximum at the depth of 350 and 600 km.