In June 1962 he won the singles title at the Lowther Open in Barnes, Surrey, England against Michio Fujii.

Ishiguro had wins over Ingo Buding and Keith Carpenter in the 1963 Wimbledon Championships, to make the third round, where he lost to Jaidip Mukerjea in straight sets.

En route he managed a surprise win over American Frank Froehling, who had been a finalist in the previous year's US Championships.

[4] In 1965, Ishiguro became the first post-war Japanese player to win a match at the Australian Championships, defeating Colin Stubs in the first round.

He then beat Jean-Noël Grinda to progress to the third round, but his run would end there, losing to second seed Fred Stolle.