The approval rate for Prime Minister Fumio Kishida's Cabinet fell 3.1 percentage points from the level in May to 35.1%, the first decline in five months, a Jiji Press survey showed.
The disapproval rate climbed 3.2 points to 35%, according to the poll conducted from Friday through Monday.
The drop in approval is believed to reflect Kishida's handling of a scandal over a controversial year-end party last year involving his son, Shotaro, who was a secretary to the prime minister at the time.