To provide an on-vehicle article installing structure to a rear panel in an automobile, for reducing vibration from an external part, even if fastening torque and tire air pressure are changed, by installing a spare tire and a repair kit storage box as the on-vehicle article.

An irregular pitch spring 14 and a lower side cylinder 16 are stored in a cylinder storage case 13 erected on the rear panel 11. The spare tire or the repair kit storage box 12 is sandwiched between a receiving member 18 and a fixed member 19, and an upper side cylinder 17 projected to the lower side of the receiving member 18 is inserted into the repair kit storage box 12. In that case, meshing between the lower side cylinder 16 and the upper side cylinder 17 is adjusted in response to a load of an object sandwiched by the receiving member 18 and the fixed member 19, and the vertical length of a cylinder 15 is adjusted, and a contraction amount of the irregular pitch spring 14 is adjusted.