吓阻理论（英语：Deterrence；德语：Abschreckung。或译：威吓理论）是犯罪学中关于（抵消）犯罪动机、在刑事政策中关于预防犯罪的一种理论观点。治乱世用重典、向毒品宣战、三振法案、吓乖计划皆属于吓阻理论的产物。

吓阻理论最初是指：透过预先宣告严刑峻罚，就能吓阻人类的犯罪行为；如果已经有人犯罪，透过严惩他们来杀鸡儆猴，便能吓阻其他人犯罪。

除了正式制度的制裁（刑罚）外，吓阻理论亦使用非正式制度的制裁概念，当中包括舆论批评、亲友的不认同等等。

Deterrence is the use of punishment as a threat to deter people from offending. Deterrence is often contrasted with retributivism, which holds that punishment is a necessary consequence of a crime and should be calculated based on the gravity of the wrong done.