The 25-year-old sensation led off the fifth inning at Yankee Stadium with a solo blast off Milwaukee Brewers pitcher Josh Hader.
He sent the changeup from Hader an estimated 432 feet to put the Yankees up 4-2.
It marked Judge's third straight game with a homer. He had tied DiMaggio's 1936 total of 29 home runs in a 7-6 loss to the Toronto Blue Jays on Wednesday.
Judge is only the second rookie to reach 30 home runs before the All Star break.
Mark McGwire had 33 at the break in 1987 on the way to establishing the major league rookie record of 49 homers in a season.
Judge's effort came in a disappointing 9-4 loss to the Brewers.
Milwaukee's Jesus Aguilar hit a tiebreaking grand slam with two outs in the top of the seventh and tied a Milwaukee record with seven runs-batted-in for the Brewers.
Milwaukee's five runs in the seventh proved enough for the victory.
source: news.abs-cbn.com
