庇古效应（Pigou Effect），又称财富效应或利率效应，古典经济学家阿瑟·庇古认为，凯恩斯效应仅仅考虑了价格下降，影响利率，进而影响私人投资，却忽略了价格下降对消费的影响。消费不仅仅是实际收入的函数，也是私人部门净财富实际价值的函数。可表示为：C=C(Y, W/P)。在未达到完全就业的情况下（经济中存在较大量失业），工资和价格水平的下降，会使得私人部门的净财富的实际价值上升，从而拉动消费需求上升。

庇古在1930年代指出：实际货币余额（M/P）是家庭财富的一部分，随着物价水平P的下降，实际货币余额（M/P）增加，消费者会感到富有，并更多地进行支出（消费）。这被称作是“庇古效应”，可以表示为：价格P下降－货币持有者更加富有－支出（自发性消费）C增加－产出Y增加。

In economics, the Pigou effect is the stimulation of output and employment caused by increasing consumption due to a rise in real balances of wealth, particularly during deflation. The term was named after Arthur Cecil Pigou by Don Patinkin in 1948.

Real wealth was defined by Arthur Cecil Pigou as the sum of the money supply and government bonds divided by the price level. He argued that Keynes' General Theory was deficient in not specifying a link from "real balances" to current consumption and that the inclusion of such a "wealth effect" would make the economy more 'self correcting' to drops in aggregate demand than Keynes predicted. Because the effect derives from changes to the "Real Balance", this critique of Keynesianism is also called the Real Balance effect.