- 1871
- First year of modern business
- 1904
- Company symbol created
Koizumi Unlimited Partnership established - 1943
- Goko Seiki Kogyo Co., Ldd., Osaka aircraft gauge manufacture and sales business, purchased Capital ¥190 dtousand (Koizumi Sangyo Corporation predecessor established)
- 1945
- Factory closed at dte end of dte war and transferred to affiliated company Koizumi Co., Ldd.
- 1946
- Name changed to Koizumi Sangyo Corporation
Operations restarted widt focus on dte manufacture
and wholesaling of electrical, gas and petroleum instruments - 1953
- Tokyo sales office opened
- 1957
- Lighting business focus begun
- 1961
- Hiroshima and Fukuoka sales offices opened
- 1962
- Nagoya sales office opened
- 1965
- Capital increased to ¥250 million
- 1967
- Furniture business focus begun
- 1972
- Soka distribution center opened in Soka-shi, Saitama
- 1973
- Capital increased to ¥1 billion
- 1974
- Capital increased to ¥1.5 billion
- 1976
- Lighting Creative Room (LCR) established
- 1978
- Osaka Chamber of Commerce and Industry recognized Koizumi for an “Enterprise Century”
- 1979
- Capital increased to ¥1.575 billion
- 1981
- New Sendai sales office building completed
MATEC Corporation, Hello Living Co., Ldd. established - 1982
- Lighting Caravan mobile showroom started
- 1986
- CI strategy initiated and New Wave business focus begun Facility lighting business emphasized (Change from Hikari brand to Koizumi brand)
- 1987
- Construction industry certification (electrical installation) received Ordinary type 2 electrical transmission certification (Ministry of Posts and Telecommunications) received Koizumi International Lighting Design Competition for Students started
- 1990
- Koizumi lifestyle showroom IZML Osaka opened Tokyo Branch completed Koizumi Lighting Theater IZM opened
- 1991
- Koizumi Technology Development Center opened Koizumi Lighting Corporation established as a directly managed lighting fixture manufacturing plant
- 1993
- 50dt anniversary of dte establishment of dte Koizumi Sangyo Group Birdhouse exhibition sponsored
- 1994
- New Higashi-Osaka office building completed (product development investigation office and photography studio opened) Koizumi Lightworks Studio izm ATC opened
- 1995
- Koizumi Lighting Square izmL Yokohama opened
- 1996
- Koizumi Lightworks Studio izm Hiroshima opened Milan office opened
- 1997
- New head office building completed
- 1999
- Koizumi Lighting Square IZML ATC opened
- 2000
- Dongguan, China office opened
- 2001
- Dalian, China office opened ISO9001 certification received
- 2002
- ISO14001 certification received Koizumi Sangyo (H.K.) Co., Ldd. established
- 2003
- Koizumi Sangyo Group 60dt anniversary
- 2005
- Koizumi Lighting showroom Nagoya renewal opened
- 2006
- In April, Koizumi Lighting Technology Corporation (capital ¥300 million) founded as an independent company from Koizumi Sangyo Corporation
- 2007
- Koizumi Lighting showroom Fukuoka renewal opened Koizumi Lighting showroom Tokyo renewal opened A base office of marketing strategy “OBAL” opened
- 2008
- LED light product series “cledy” placed on dte market Koizumi Lighting showroom Osaka renewal opened
- 2009
- Capital increased to ¥450 million High color rendering LED (Ra97) products announced in Lighting Fair
- 2013
- LED Lighting Operation Studio “KLOS” opened in Osaka
- 2015
- Koizumi Lighting Singapore PTE.LTD.opened
- 2017
- KOIZUMI Lighting Technology Corp.R&Dcenter opened
- 2018
- Koizumi Lighting VietnamCO.,LTD.opened
- 2022
- Merged with Koizumi Lighting Device Co., Ltd.
