Toshisada Oka, a member of the House of Councilors who once served as parliamentary vice minister at the Science and Technology Agency, died Monday of liver failure at Tokyo Teishin Hospital, his family said. He was 66.

A former bureaucrat at the Posts and Telecommunications Ministry, Oka entered politics in 1992, winning his first seat in the Upper House election under the proportional representation system. As a member of the ruling Liberal Democratic Party, he was re-elected in 1998.

As a result of Oka's death, Tatsuo Shimizu, a 66-year-old former Upper House member, will move up the LDP's candidate list for the 1998 proportional representation election and take over Oka's seat.

Oka is survived by his wife, Yasuko.