JEOL (日本電子, Nihon Denshi^?, Nihon meaning Japan and Denshi meaning electron) is a manufacturer of electron microscopes and other scientific instruments. Its headquarters are in Tokyo, Japan, with 25 subsidiaries (as of March 2007) and two associated companies.

JEOL Ltd. has four business segments. Electron Optics manufactures scanning electron microscopes, transmission electron microscopes and scanning probe microscopes, along with related equipment. The Analytical Instruments section's products include mass spectrometers, nuclear magnetic resonance and electron spin resonance equipment. The Industrial Equipment segment covers a range of equipment particularly targeted at the semiconductor industry, such as electron beam sources, wafer process monitors, and plasma gun series. Finally, the Medical Equipment segment manufactures automatic analysis devices, clinical diagnostic systems and amino acid analyzers.

For the year 2006, JEOL reported net sales of 93,291 million Japanese yen. [1]

The company was founded in 1949 as the Japan Electron Optics Laboratory Co., Ltd in Mitaka, Tokyo, in 1949, and produced its first commercial model transmission electron microscope the year later, although a prototype microscope had been sold to Mitsubishi prior to the founding of the company. Overseas sales began in 1956 with the sale of a system to France. In 1961, the company was renamed JEOL Ltd, with the first overseas subsidiary JEOL CO (USA) INC., established in 1962 and headquartered in Peabody, MA.