Shimano, Inc. (株式会社シマノ, Kabushiki-gaisha Shimano), originally Shimano Iron Works (島野鐵工所) and later Shimano Industries, Inc. (島野工業株式会社), is a Japanese multinational manufacturing company for cycling components, fishing tackle and rowing equipment, which also produced golf supplies until 2005 and snowboarding gear until 2008. Named after founder Shozaburo Shimano (島野庄三郎, 1894–1958) and headquartered in Sakai, Osaka Prefecture, the company has 32 consolidated and 11 unconsolidated subsidiaries, with the primary manufacturing plants based in Kunshan (China), Malaysia and Singapore.

In 2017, Shimano had net sales of US $3.2 billion, 38% in Europe, 35% in Asia, and 11% in North America. Bicycle components represented 80%, fishing tackle 19%, and other products 0.1%. The company is publicly traded, with 93 million shares of common stock outstanding.

They are also the official neutral support for most of the UCI World Tour.

Shimano sales constitute an estimated 85% of the global bicycle component market by value. Its products include drivetrain, brake, wheel, and pedal components for road, mountain, track, and hybrid bikes. The components include cranksets comprising cranks and chainrings, bottom brackets, chains, rear chain sprockets and cassettes, front and rear wheel hubs, gear shift levers, brakes, brake levers, cables, and front and rear dérailleurs. Shimano Total Integration (STI) is Shimano's integrated shifter and brake lever combination for road bicycles. The Italian firm Campagnolo as well as US-based SRAM are Shimano's primary competitors in the cycling marketplace.

When the 1970s United States bike boom exceeded the capacity of the European bicycle component manufacturers, Japanese manufacturers SunTour and Shimano rapidly stepped in to fill the void. While both companies provided products for all price ranges of the market, SunTour also focused on refinement of existing systems and designs for higher-end products, while Shimano initially paid more attention to rethinking the basic systems and bringing out innovations such as Positron shifting (a precursor to index shifting) and front freewheel systems at the low end of the market. In the 1980s, with Shimano pushing technical innovation and lower prices, the more traditional European component manufacturers lost significant market presence. During this period, in contrast to the near-universal marketing technique of introducing innovations on the expensive side of the marketplace and relying on consumer demand to emulate early adopters along with economy of scale to bring them into the mass market, Shimano and SunTour (to a lesser extent) introduced new technologies at the lowest end of the bicycle market, using lower cost and often heavier and less durable materials and techniques, only moving them further upmarket if they established themselves in the lower market segments.

In the 1980–1983 period, Shimano introduced three groupsets with "AX" technology: Dura-Ace and 600 (high-end), and Adamas in the low-end. Features of these components include aerodynamic styling, center-pull brakes, brake levers with concealed cables, and ergonomic pedals. By 1985 Shimano introduced innovation only at the highest quality level (Dura-Ace for road bikes and XT for mountain bikes), then trickled the technology down to lower production levels as it became proven and accepted. Innovations include index shifting (known as SIS, Shimano Index System introduced in 1984), freehubs, dual-pivot brakes, 8-9-10-speed drivetrains, and the integration of shifters and brake levers. Also, these components could only work properly when used with other Shimano components; for example, its rear derailleurs have to be used with the correct Shimano gear levers, cables, freehub, and cassette. SunTour tried to catch up, but by the end of the 1980s they had lost the technological and commercial battle, and Shimano had become the largest manufacturer of bicycle components in the world.

Shimano's marketplace domination that developed in the 1990s quickly led to the perception by some critics that Shimano had become a marketplace bully with monopolistic intentions. This viewpoint was based on the fact that Shimano became oriented towards integrating all of their components with each other, with the result being that if any Shimano components were to be used, then the entire bike would need to be built from matching Shimano components. The alternative perspective is that by controlling the mix of components on the bicycle, a manufacturer such as Shimano can control how well their own product functions. Shimano's primary competitors (Campagnolo and SRAM) also make proprietary designs that limit the opportunity to mix and match componentry.

In 2003 Shimano introduced "Dual Control" to mountain bikes, where the gear shift mechanism is integrated into the brake levers. This development was controversial, as the use of Dual Control integrated shifting for hydraulic disc brakes required using Shimano hydraulic disc brakes, locking competitors out of the premium end of the market. However, with their 2007 product line, Shimano moved back to making separate braking and shifting components fully available in addition to the integrated "Dual Control" components, a move to satisfy riders that wished to use Shimano shifting with other brands of disc brakes.