A photoacoustic microscope apparatus includes a light source that emits excitation light which generates photoacoustic waves, an objective lens which focuses the excitation light on a specimen, a scanning unit which moves a focused position of the excitation light on the specimen, a photoacoustic-wave detecting unit which has a sensor unit that detects a photoacoustic wave generated, and an image constructing unit which constructs an image based on data from the photoacoustic-wave detecting unit. For the sensor unit, an angle of a range which is capable of receiving the photoacoustic wave incident on the sensor unit is larger than an angle corresponding to a numerical aperture on a side illuminated of the objective lens.