Gaffe-prone Finance Minister Taro Aso has disparaged the sex of a junior lawmaker in the ruling Liberal Democratic Party who might quit over allegations that she assaulted one of her secretaries.

"If you only look at her academic background, it's impeccable, but she is a woman," Aso told a group of LDP members in his faction during a meeting Saturday in Shibata, Niigata Prefecture.

According to a report in the weekly magazine Shukan Shincho that hit newsstands Thursday, second-term Lower House lawmaker Mayuko Toyota was in the back seat of a car being driven by one of her secretaries on May 20 when the driver took the wrong highway exit.

Toyota allegedly called him "baldy" and struck him several times on the head and face, reportedly injuring the man.

She hit the driver on seven occasions between May 19 and May 21, an official at Toyota's office said, adding that she apologized after he had already quit.

Toyota graduated from the University of Tokyo in 1997 and earned her master's degree from the Harvard School of Public Health in 2002. She was a health ministry bureaucrat until she won election to the Lower House in 2012.

In his speech in Niigata, Aso said a ministry source once told him the ministry had been trying to get rid of her, and it turned out that Nagatacho, the nation's political capital, took her in.

Aso added that 119 new lawmakers, including Toyota, won seats in the 2012 election and that it is only natural that their characters vary.