Ishii was born in Shizuoka Prefecture, Japan, and started playing golf at the age of 15.

[1] Ishii won a number of events on the Japanese and Asian circuits through the 1950s and 1960s.

One of his top triumphs was at the 1964 Capitol Hills Open in Manila, Philippines on the Far East Circuit.

Ishii was tied for the lead with Australian golfer Peter Thomson at the beginning of the fourth round.

[2] His good play helped him earn three consecutive special foreign invitations to the Masters in the mid-1960s.