Prystor was one of the few men in Poland with direct access to Pilsudski, at any time of the day and night. He lived in the Belweder, together with the Marshal. In 1929, he was briefly manager of the Personal Officer of the Ministry of Military Affairs. On April 26, 1929, he was named the Minister of Labour and Social Services in the government of Kazimierz Bartel. Working under very difficult conditions, as Poland was affected by the Great Depression, Prystor managed to increase unemployment benefits and increase the program of Public works. Furthermore, he dissolved the structures of government health insurance program, which were in the hands of oppositional Polish Socialist Party. Among others, Prystor introduced government commissars into local offices of the health insurance.