Abstract: Disclosed is a photo-pressure sensitive recording sheet developing apparatus in which vibratory pressure generated by an ultrasonic wave generating means is applied to a photo/pressure sensitive recording sheet using microcapsules carrying a latent image formed through exposure to thereby develop the photo/pressure sensitive recording sheet by the vibratory pressure. Preferably, the ultrasonic wave generating means is formed as a single resonance system and has parallel surfaces opposite to each other, each of the opposite surfaces having a vibration mode so that the opposite surfaces are displaced in the directions opposite to each other and substantially along a vertical axis of the opposite surfaces.