Campaign finance refers to the fundraising and spending that political campaigns do in their election races. As campaigns have many expenditures, ranging from the cost of travel for the candidate and others to the purchasing of air time for TV advertisements, candidates often devote substantial time and effort raising money to finance campaigns.

Although the political science literature indicates that most contributors give to support candidates with whom they are already in agreement, there is wide public perception that donors expect illegitimate government favors in return. (such as specific legislation being enacted or defeated) so some have come to equate campaign finance with political corruption and bribery. These views have led some governments to reform fundraising sources and techniques in the hope of eliminating perceived undue influence being given to monied interests. Another tactic is for the government, rather than private individuals and organizations, to provide funding for campaigns.

Democratic countries have differing regulations on what types of donations to political parties and campaigns are acceptable.

The causes and effects of different campaign finance rules are studied in a number of disciplines including political science, economics and public policy.