Small repeating earthquakes are earthquakes that repeatedly occur at the same location. These earthquakes are thought to be caused by repeated ruptures of small locked patch on a fault plane due to a creep in the surrounding area. Taking advantage of the occurrence mechanism, we can estimate the creep (slow slip) from the activity of repeating earthquakes. The estimated fault creep in Japan show heterogeneous fault locking along the plate boundary that is consistent with the location of previous large earthquakes and geodetic estimations of fault locking. The high-resolution spatial distribution of interplate creep also suggest that the upper plate controls the interplate locking at the southern part along the Japan trench. The temporal changes of creep show most interplate earthquakes have afterslips and periodic slow slip also occur in a wide area along the plate boundary offshore Tohoku and correlate with seismicity. These results suggest slow slip is an important process that release stress on the fault and mutually related with earthquake activities.