Company History
| May 1963 | NANKAI DENKO CORPORATION was established after the merger of four electrical construction companies, Tokushima, Nankai, Iyo and Kagawa. Established as a business corporation (Kabushiki Kaisha). Four branches in Tokushima, Kochi, Ehime, Kagawa, and the Osaka regional office (current Osaka headquarters) were established. |
|---|---|
| December 1965 | The corporate name was changed to SHIKOKU ELECTRIC CONSTRUCTION CORPORATION. |
| March 1966 | Tokyo regional office (current Tokyo headquarters) was established. |
| May 1973 | Okayama business office was established. |
| November 1979 | The company shares were listed on the First Section of Tokyo Stock Exchange. |
| November 1989 | The corporate name was changed to YONDENKO CORPORATION. |
| November 1992 | Bunri business office was established. |
| November 1994 | Acquisition of the shares of Kochi Create Corporation |
| October 1996 | ACCEL-TOKUSHIMA CORPORATION was established. |
| February 1997 | YONKO BUSINESS CORPORATION was established. |
| April 1997 | CADEWA SERVICE CORPORATION was established. |
| October 1997 | ACCEL-MATSUYAMA CORPORATION and Kagawa Create Corporation were established. |
| February 2006 | Utazu Kyushoku Service Corporation was established. |
| November 2007 | Tokushima City High School PFI Service Corporation was established. |
| November 2010 | Tokushima Agriculture, Forestry, and Fisheries PFI Service Corporation was established. |
| April 2011 | Ozu Kyushoku PFI Service Corporation was established. |
| March 2012 | Tohoku business office was established. |
| December 2012 | Nio Solar Power Generation Corporation was established. |
| September 2013 | YONKO SOLAR CORPORATION was established. |
| March 2014 | Kuwano Solar Power Generation Corporation was established. |
| August 2016 | Kasaoka Kyusyoku PFI Service Corporation was established. |
| October 2016 | Ozu School PFI Service Corporation was established. |
| December 2016 | Matsuyama School Air Conditioner PFI Service was established. |
| August 2017 | Seiyo City Planning Service was established. |
| January 2018 | Tokushima Police PFI Service was established. |
| February 2018 | Acquisition of the shares of Arimoto Oncho Corporation. |
| July 2018 | Acquisition of the shares of AI DENKI TSUSHIN Corporation. |
| August 2018 | Saizyo School Air Conditioner PFI Service was established. |
| October 2018 | Acquisition of the shares of RYOUEI SETSUBI KOUGYOU Corporation. |
| November 2018 | Yondenko Vietnam Company Limited was established. |
| August 2019 | Acquisition of the shares of KANSAISETUBI Corporation. |
| March 2020 | Acquisition of the shares of Suzuki Architectural Design Office. |
| May 2020 | Kobe and Kyoto business offices were established. |
| April 2021 | Acquisition of the shares of YOKOYAMAKOGYO Corporation. |
| July 2021 | Okinawa business office was established. |
| December 2021 | Acquisition of the shares of BELTEC Corporation. |
