A photoacoustic image generation apparatus comprising: a laser source unit capable of emitting a plurality of pulse laser beams having different wavelength respectively, the laser source unit including a laser rod, an excitation light source that irradiates the laser rod with excitation light, an optical resonator having a pair of mirrors (53, 54) facing each other with the laser rod interposed therebetween, a Q switch which is inserted into the optical resonator, wavelength selection means that includes a plurality of band pass filters having different transmission wavelengths and selectively inserts the plurality of band pass filters into a light path of the optical resonator, and driving means that drives the wavelength selection means so that the band pass filters inserted into the light path of the optical resonator are sequentially and continuously switched in a predetermined order; and an acoustic wave unit that generates a photoacoustic image, the acoustic wave unit including detection means that detects a photoacoustic signal generated within an object when the object is irradiated with the pulse laser beams having the plurality of wavelengths, and generates pieces of photoacoustic data corresponding to the respective wavelengths, intensity ratio extraction means that extracts a magnitude relation between relative signal intensities of the pieces of photoacoustic data corresponding to the respective wavelengths, photoacoustic image construction means that generates a photoacoustic image on the basis of the extracted magnitude relation, and a trigger control circuit that causes the laser rod to be irradiated with excitation light from the excitation light source while controlling the driving means so that the band pass filters inserted into the light path of the optical resonator are switched at a predetermined switching speed, and after the irradiation with the excitation light, turns on the Q switch at a timing when the wavelength selection means inserts the band pass filter, having a transmission wavelength corresponding to a wavelength of the pulse laser beam to be emitted, into the light path to emit the pulse laser beam. a laser source unit capable of emitting a plurality of pulse laser beams having different wavelength respectively, the laser source unit including a laser rod, an excitation light source that irradiates the laser rod with excitation light, an optical resonator having a pair of mirrors (53, 54) facing each other with the laser rod interposed therebetween, a Q switch which is inserted into the optical resonator, wavelength selection means that includes a plurality of band pass filters having different transmission wavelengths and selectively inserts the plurality of band pass filters into a light path of the optical resonator, and driving means that drives the wavelength selection means so that the band pass filters inserted into the light path of the optical resonator are sequentially and continuously switched in a predetermined order; and an acoustic wave unit that generates a photoacoustic image, the acoustic wave unit including detection means that detects a photoacoustic signal generated within an object when the object is irradiated with the pulse laser beams having the plurality of wavelengths, and generates pieces of photoacoustic data corresponding to the respective wavelengths, intensity ratio extraction means that extracts a magnitude relation between relative signal intensities of the pieces of photoacoustic data corresponding to the respective wavelengths, photoacoustic image construction means that generates a photoacoustic image on the basis of the extracted magnitude relation, and a trigger control circuit that causes the laser rod to be irradiated with excitation light from the excitation light source while controlling the driving means so that the band pass filters inserted into the light path of the optical resonator are switched at a predetermined switching speed, and after the irradiation with the excitation light, turns on the Q switch at a timing when the wavelength selection means inserts the band pass filter, having a transmission wavelength corresponding to a wavelength of the pulse laser beam to be emitted, into the light path to emit the pulse laser beam.