To provide a component system for a vehicular meter resolving complicated work when an user installs a retrofiited vehicular meter to a vehicle, and to provide a selling method capable of purchasing only necessary thing by the minimum cost at the time of purchasing, eliminating waste, and having excellent cost performance.

In the retrofiited vehicular indicates a measured value by receiving data from each sensor provided on a vehicular engine and peripheral control equipment and outputting date of water temperature, oil temperature, exhaust temperature, hydraulic pressure, fuel pressure, supercharging pressure, intake pressure, and the like, packet servers divided into groups according to the characteristic of each sensor are individually provided. To the packet server, the retrofitted meter for indicating a corresponding measured value can be connected. Therefore, the component system for the retrofitted vehicular meter resolving complicated work when attached to the vehicle and having very good mounting performance can be provided.