搭便车问题（free rider problem）由经济学家和社会学家曼柯·奥尔逊 (Mancur Olson) 于1965年在《集体行动的逻辑》(The Logic of Collective Action: Public Goods and the Theory of Groups)(1965)一书中所提出。其基本含义是不付成本而坐享他人之利。是一种发生在公共财上的问题。指一些人需要某种公共财，但事先宣称自己并无需要，在别人付出代价去取得后，他们就可不劳而获的享受成果。

在日常生活中常可找到搭便车的例子，例如许多轮船公司不肯兴建灯塔，他们可以获得同样的服务，此种搭便车问题会影响公共政策的顺利制定及有效运行。

In economics, the free rider problem occurs when those who benefit from resources, goods, or services do not pay for them, which results in an under-provision of those goods or services. The free rider problem is the question of how to limit free riding and its negative effects in these situations. The free rider problem may occur when property rights are not clearly defined and imposed. An opposite concept is that of a forced rider.