quaestor (kwĕs`tôr), Roman magistrate, with responsibility for the treasury; in early times a quaestor also had judicial powers. At first there were two quaestors. Sulla named 20, and Caesar set 40 as the number (45 B.C.), but Augustus reduced them to 20. Quaestors were in theory deputies for consuls, praetors, or proconsuls. A quaestorship was the first magistracy sought by an ambitious young man.