The announcement was made on Friday by Toyota and his Cerumo team, for which the 48-year-old has driven continuously since the 1999 season.
In that time, he scored three GT500 titles in 2001, '05 and '13 while racking up 19 wins, putting him second to Tsugio Matsuda in the all-time list, and 24 pole positions, an outright series record.
In a short statement, Tachikawa said: "It has been with the help of Toyota, TCD [Toyota Customising and Development], Cerumo, [long-time team title sponsor] ZENT and Bridgestone, as well as the support of many friends and family, that I have been able to come this far.
"I want to thank you all for respecting my feelings until the end. My heart is full of gratitude.
"The GTA has always provided a wonderful stage known as Super GT, and being able to compete on this stage has been a blessing for me.
"I decided to make this announcement in the middle of the season so that those who have been supporting me have the chance to see my last races properly. I will give it my all for the remaining races, so please support me until the end."
Source: Autosport