Fault diagnosis system

The present invention improves the accuracy of vehicle fault diagnosis. A failure diagnosis system (1) is provided with: a data acquisition unit (40) that associates and acquires travel environment data including driving operation data indicating at least a driving operation of a target vehicle to be subjected to failure diagnosis, and actual travel result data indicating an actual travel result based on the travel environment data; an appropriate range setting unit (42) that derives an appropriate range of actual travel results based on the travel environment data for vehicles of the same type as the target vehicle; and a malfunction determination unit that determines the presence or absence of a malfunction in the target vehicle by determining whether the actual travel result data is included in an appropriate range. 本发明使车辆的故障诊断的精度提升。故障诊断系统(1)具备数据取得部(40)，其将行驶环境数据与表示基于行驶环境数据的实际的行驶结果的实际行驶结果数据相关联而取得，上述行驶环境数据包括成为故障诊断的对象的对象车辆的至少表示驾驶操作的驾驶操作数据；适当范围设定部(42)，其导出车种与对象车辆的车种相同的车辆的、基于行驶环境数据的实际的行驶结果的适当范围；以及故障判断部，其通过判断实际行驶