抗爆剂，又称抗震剂、汽油抗爆剂、辛烷值提升剂。是提高辛烷值，以防止或减轻汽油在引擎内燃烧时产生的爆震。 烷基铅在1923年开始成为好用的抗爆剂，此外，四甲基铅、四乙基铅及其混合物也常被使用。但这类含铅的抗爆剂，会使汽车排放出污染空气的有害长体，因此在无铅汽油中，改使用其他类的防爆剂，如甲基环戊二烯三羰基锰（MMT）等锰化合物的抗爆剂。

An antiknock agent is a gasoline additive used to reduce engine knocking and increase the fuel's octane rating by raising the temperature and pressure at which auto-ignition occurs.

The mixture known as gasoline or petrol, when used in high compression internal combustion engines, has a tendency to knock (also called "pinging" or "pinking") and/or to ignite early before the correctly timed spark occurs (pre-ignition, refer to engine knocking).