Multi-axle suspension system for a vehicle

A suspension apparatus of a multi-axle vehicle capable of realizing high traveling stability is provided. For this purpose, the suspension apparatus forms a quadric link structure (31) by a vehicle body (9), a front link (21) with an upper end portion being connected to the vehicle body with a pin and a lower end portion being in a vicinity of a front axle, a rear link (22) with an upper end portion being connected to the vehicle body with a pin and a lower end portion located in a vicinity of a rear axle, and a connecting link (1) for connecting portions in vicinities of respective lower end portions of the front and rear links, and a side length at a side of the connecting link is made shorter than a side length at a vehicle body side.