A printed material holding device includes a printed material tray for receiving printed media, an adjustable mechanism and a transmission mechanism. The adjustable mechanism includes a driving device, a first gear assembly, a second gear assembly, a rotatable member, and a moving member engaged with the rotatable member. The moving member includes a roller engaged with the second gear assembly. The transmission mechanism includes a mounting plate and a stopper piece disposed on an edge of the mounting box. The first gear assembly meshes with the driving device and is engaged with the rotatable member, and the second gear assembly is engaged with the first gear assembly and secured to the moving member.