To enhance sound insulation performance of a grommet for wire harnesses which is attached into a through hole in a car body panel.

A first member and a second member made of rubber or elastomer are engaged and coupled with each other. The first member includes a first small-diameter tube through which the wire harness passes in a close contact manner, a bellow-shaped radial protrusion which continues to the longitudinal one end of the first small-diameter tube, and an outer tube which continues to the peripheral end of the radial protrusion. The periphery on the protrusion side of the outer tube is provided with a circular car-body locking recess. The second member is equipped with a second small-diameter tube through which the wire harness passes in close contact manner, and a conical tube which protrudes with its diameter expanded from the longitudinal one end of the second small-diameter tube. The inner circumferential face of the first member is provided with a locked part. The tip on the diameter-expanded side of the conical tube of the second member is provided with a locking part which engages with the locked part. By engaging the first member with the second member, the first small-diameter part and the second small-diameter part face each other at both longitudinal ends along the axis, and sealed space for sound insulation is formed therebetween.