Abstract: A fitting structure for a connector housing can maintain a stable vibration absorbing function. A flange (14) of a connector housing (10) is provided on the periphery with an outer annular retaining wall (15). A rubber sheet (20) is contained in an interior of the connector housing (10). The connector housing (10) is attached to a body (E) of an engine by means of bolts (B) and nuts (N). When fattening bolts (B) and nuts (N), the rubber sheet (20) is compressed. In a conventional fitting structure, the compressed rubber sheet (20) expands laterally to bulge out of the flange (14). Since the outer annular retaining wall (15), however, serves to limit the lateral expansion of the rubber sheet (20) so that the rubber sheet (20) does not bulge out from the flange (14), it is possible to prevent the rubber sheet (20) from changing its physical and/or chemical nature and to effectively maintain its vibration absorbing function.