An apparatus configured to be installed in a vehicle comprising: an impact absorbing portion that is part of an apparatus main body; and a support member to which the impact absorbing portion is fixed, wherein the apparatus comprises: an opposing fixing member, a fastening member that fastens the support member and the opposing fixing member together, and an opening in the impact absorbing portion in which the fastening member is inserted; characterized in that the support member and the opposing fixing member are fastened together by the fastening member, with the impact absorbing portion disposed between the support member and the opposing fixing member; a moving clearance (δ) provided in an impact acting direction between the opening and the fastening member; a protrusion (17, 117, 217, 317) provided on one of the opposing fixing member and the impact absorbing portion, and a recess (12, 112, 212, 312) provided in another of the opposing fixing member and the impact absorbing portion, or a protrusion (17, 117, 217, 317) provided on one of the support member and the impact absorbing portion, and a recess (12, 112, 212, 312) provided in another of the support member and the impact absorbing portion; the protrusion (17, 117, 217, 317) and the recess (12, 112, 212, 312) are configured to be fitted to position the impact absorbing portion and the support member in the impact acting direction; and the protrusion (17, 117, 217, 317) is configured to be separated when a shearing force in the impact acting direction acts on the protrusion (17, 117, 217, 317). an impact absorbing portion that is part of an apparatus main body; and a support member to which the impact absorbing portion is fixed, wherein the apparatus comprises: an opposing fixing member, a fastening member that fastens the support member and the opposing fixing member together, and an opening in the impact absorbing portion in which the fastening member is inserted; characterized in that the support member and the opposing fixing member are fastened together by the fastening member, with the impact absorbing portion disposed between the support member and the opposing fixing member; a moving clearance (δ) provided in an impact acting direction between the opening and the fastening member; a protrusion (17, 117, 217, 317) provided on one of the opposing fixing member and the impact absorbing portion, and a recess (12, 112, 212, 312) provided in another of the opposing fixing member and the impact absorbing portion, or a protrusion (17, 117, 217, 317) provided on one of the support member and the impact absorbing portion, and a recess (12, 112, 212, 312) provided in another of the support member and the impact absorbing portion; the protrusion (17, 117, 217, 317) and the recess (12, 112, 212, 312) are configured to be fitted to position the impact absorbing portion and the support member in the impact acting direction; and the protrusion (17, 117, 217, 317) is configured to be separated when a shearing force in the impact acting direction acts on the protrusion (17, 117, 217, 317). an opposing fixing member, a fastening member that fastens the support member and the opposing fixing member together, and an opening in the impact absorbing portion in which the fastening member is inserted; characterized in that the support member and the opposing fixing member are fastened together by the fastening member, with the impact absorbing portion disposed between the support member and the opposing fixing member; a moving clearance (δ) provided in an impact acting direction between the opening and the fastening member; a protrusion (17, 117, 217, 317) provided on one of the opposing fixing member and the impact absorbing portion, and a recess (12, 112, 212, 312) provided in another of the opposing fixing member and the impact absorbing portion, or a protrusion (17, 117, 217, 317) provided on one of the support member and the impact absorbing portion, and a recess (12, 112, 212, 312) provided in another of the support member and the impact absorbing portion; the protrusion (17, 117, 217, 317) and the recess (12, 112, 212, 312) are configured to be fitted to position the impact absorbing portion and the support member in the impact acting direction; and the protrusion (17, 117, 217, 317) is configured to be separated when a shearing force in the impact acting direction acts on the protrusion (17, 117, 217, 317).