A drive-condition setting device applied to an optical scanning apparatus having a fiber and an actuator that vibrates a distal end of the fiber, the drive-condition setting device detects a scan pattern of the illumination light output from the fiber, measures resonance frequencies in the x direction and the y direction of the fiber, sets a drive frequency and a drive voltage based on the resonance frequencies such that conditional expressions below are satisfied: when fx>fy, fd fx and Vx≤Vy (2), and when fx≤fy, fd fy and Vx≥Vy (4) where fd denotes the drive frequency, Vx denotes a maximum voltage of a X direction drive signal, and Vy denotes a maximum voltage of a y direction drive signal.