Kojiro Yoshinaga (吉永宏二郎, Yoshinaga Kojirō); born 8 June 1961 in Tokyo) is a former Japanese rugby union player and coach.
After his graduation, Yoshinaga started to play for Mazda Motors Corporation in the All-Japan Rugby Company Championship, in all of his career.
Yoshinaga was first capped for Japan in the match against Korea, at Bangkok, on 29 November 1986.
He also was capped for the 1987 Rugby World Cup, playing 2 matches in the tournament, making him the only player in Mazda Motor Company's history to take part in a Rugby World Cup.
[1] Yoshinaga was also present in the Japanese squad who defeated Scotland in 1989.