To cope with a difference in a dimension of a tip tool with a simple constitution, without using an adjusting mechanism for a dust collector.

This dust collector 30 is slidably installed in the longitudinal direction in a housing 2 by fitting of a rail part 27 arranged on an under surface of the housing 2 of a hammer drill 1 and guide parts 45 and 45 arranged in a casing 31, and a fixing mechanism for fixing the dust collector 30 in an optional slide position, is arranged between the housing 2 and the dust collector 30.