黑市，又称地下市场，即不依官方法定的市场活动，是一种地下经济。

黑市交易活动是黑社会的经济势力来源之一，是政府打击有组织非法社团的重点项目。黑金贿选也是黑市活动。

另外货品高于法定价格，窃取或伪造有定量的配给票证，按官方价格外还另付其他费用，也归类黑市。

A black market, underground economy, or shadow economy is a market characterized by some form of noncompliant behavior with an institutional set of rules. If the rule defines the set of goods and services whose production and distribution is prohibited by law, non-complaince with the rule constitutes a black market trade since the transaction itself is illegal. Parties engaging in the production or distribution of prohibited goods and services are members of the illegal economy. Examples include the drug trade, prostitution, illegal currency transactions and human trafficking. Violations of the tax code involving income tax evasion constitutes membership in the unreported economy. Because tax evasion or participation in a black market activity is illegal, participants will attempt to hide their behavior from the government or regulatory authority. Cash usage is the preferred medium of exchange in illegal transactions since cash usage does not leave a paper trail. Common motives for operating in black markets are to trade contraband, avoid taxes and regulations, or skirt price controls or rationing. Typically the totality of such activity is referred to with the definite article as a complement to the official economies, by market for such goods and services, e.g. "the black market in bush meat".