Rumer lectured at the Novosibirsk teachers' training institute, held a position of the head of the Theoretical Physics Department at the East-Siberian Branch of the Academy of Sciences of the USSR from 1953 to 1957. In 1957 he was appointed the director of the Radio Physics and Radio Electronics Institute which was the first physical institute in Novosibirsk. The institute was merged with the Semiconductor Physics Institute in 1964. Rumer worked at the Sobolev Institute of Mathematics for some time and later at the Budker Institute of Nuclear Physics. He carried out educational work at Novosibirsk State University for almost 20 years and retired in 1972. Rumer died on 1 February 1985 in Akademgorodok, he was buried at the Yuzhnoye Cemetery. The scientist was survived by his second wife Olga Mikhailova (1921–2011), son Mikhail Mikhailov and daughter Tatyana Mikhailova. Rumer and Mikhailova met in 1946 while working together in Taganrog, and married soon after that. Both of their children became scientists.