PURPOSE: To provide a voice synchronizing method of a slide projector which eliminates the need for using any special deck or special device.

CONSTITUTION: A slide projector SP has a microcomputer 1 built in. The slide projector SP also has a keyboard 2 fixed thereto and has a film feeder 3, a focus controller 4 and a lamp controller 5 all built in. A signal selected via the keyboard 2 is transmitted to a variety of operating devices 3, 4, 5 by the microcomputer 1 and is output to a tape deck TD and recorded on the R channel of tape T as a synchronizing signal. During playback, time microcomputer 1 operates the variety of operating devices 3, 4, 5 according to the synchronizing signal from the tape T.