Pachinko (パチンコ) is a device used for gambling, described as a cross between a pinball machine and a slot machine. It is said to have been invented sometime after World War II in Nagoya, though the date is sometimes questioned. They are widespread in Japan in establishments called "pachinko parlors", which also often feature a small number of slot machines.

The player purchases a large number of small steel balls which are inserted, in bulk, into the machine. Originally, machines had a spring-loaded lever for shooting the balls, but these days they have a round "throttle" that merely controls how quickly the balls are shot. The balls then drop through an array of pins, and usually simply fall through to the bottom, but occasionally fall into certain gates which make the machine pay out more balls.

Most current machines include a slot-machine (these are called "pachi-slo"), and the big winnings are ultimately paid not from the balls falling into gates, but from the slot machine matches that follow. In fact, many modern machines do not use the balls at all to determine winnings; they are based strictly on electronic random number generators.

The winnings are in the form of more balls, which the player may use to keep playing or exchange for prizes such as pens or cigarette lighters. Cash cannot be paid out according to Japanese law, but players can then exchange prizes for cash at small centres located nearby, but separate from the parlors. Such pseudo-cash gambling is theoretically illegal in Japan, and so the exchanges are run by organised crime. Arrests for partaking in such exchanges are unknown, however.

Pachinko parlors share the reputation of slot machine dens and casinos the world over—garish decoration, over-the-top architecture, the smell of tobacco, the constant din of the machines, and players entranced for hours in their games. Pachinko has apparently thrived through Japan's recession of the 1990s, but it may struggle to attract younger players in future.