A photoacoustic imaging apparatus is equipped with an extracting section that extracts position data regarding the positions of each of a plurality of peaks in electrical signals that photoacoustic waves have been converted into, and positive/negative data that indicates whether the peaks are positive or negative. An image generating section administers chromatic adjustments to an image region corresponding to a signal region sandwiched between adjacent peaks based on the position data in the case that the positive/negative data for the adjacent peaks are in the order of positive then negative in temporal series, in order to facilitate discrimination of the pair of adjacent peaks and the signal region as being a single tissue system. Thereby, discrimination of a region between two lines is facilitated in photoacoustic imaging, even in cases that the boundary between a comparatively large tissue system and another tissue system is displayed as two lines.
