Aoki was placed on the 15-day disabled list Wednesday. He has not played since he was hit by a pitch Saturday against the Los Angeles Dodgers.
Aoki had been in the lineup for Tuesday night's game against the San Diego Padres but felt pain in the leg while warming up.
"I was definitely surprised," he told reporters Tuesday. "I came here ready to play. It was really weird that it got worse from that point."
Aoki has enjoyed a solid first season with the Giants, hitting .317 with 33 runs scored and 19 RBIs as their leadoff hitter. He's fourth among outfielders in the latest NL All-Star voting.
Aoki strikes out less often than any player in MLB this season (5.8 percent of at-bats). He's also ninth in batting average and ranks in the top 20 in steals and on-base percentage.
Travis Ishikawa's had his contract purchased from Triple-A and he was added to the Giants' 25-man roster to replace Aoki.