公共物品（Public good，又译公共财产）在经济学的解释里，是一种财货，从消费方面的观点上，具有「非竞争性」（或称「非独享性」、「共享性」、“非敌对性”）；从供给方面的观点上，具有「非排他性」。

公共物品的效用不可分割地影响整个公众，而不管其中任何个人是否愿意消费。

在现实生活中，几乎没有完全的非敌对性，以及无法排他性的财货。而大略具备这两种特性的财货，称为「公共物品」。例如空气、国防、知识等。如果每一位消费者的边际成本趋近于零，我们称这种公财为「纯公共物品」。

经济学家认为公共物品应该由政府提供或者有政府干预。

In economics, a public good is a good that is both non-excludable and non-rivalrous in that individuals cannot be effectively excluded from use and where use by one individual does not reduce availability to others. Gravelle and Rees: "The defining characteristic of a public good is that consumption of it by one individual does not actually or potentially reduce the amount available to be consumed by another individual". It also can be described as something that is useful for the entire population as is education and infrastructure. This is in contrast to a common good which is non-excludable but is rivalrous to a certain degree.