An imaging apparatus for diagnosis that generates an ultrasound tomographic image and an optical tomographic image of a diagnosis target site of a subject by using a catheter which rotatably accommodates an imaging core provided with an ultrasound transceiver that transmits and receives an ultrasound wave and an optical transceiver that transmits and receives light, the imaging apparatus for diagnosis comprising: a motor drive unit that is connected to the catheter and rotates the imaging core; and conversion means to which a pulse signal corresponding to rotation of the imaging core is input and which converts a repetition frequency of the input pulse signal into a converted pulse signal in accordance with a set number of radially-aligned lines configuring one frame of the ultrasound tomographic image; characterized in that the imaging apparatus for diagnosis further comprises: means that generates a drive signal for the ultrasound transceiver so as to obtain the ultrasound tomographic image with the number of lines based on the converted pulse signal and that transmits the generated drive signal to the ultrasound transceiver via the motor drive unit; and generating means that determines a valid pulse in accordance with the number of lines from the converted pulse signal and that generates a pulse signal representing a timing of sampling of an optical coherence signal for generating the optical tomographic image having a pulse train selected, based on the valid pulse from a pulse signal representing a cycle of a light source generating light for interfering with light from the optical transceiver. a motor drive unit that is connected to the catheter and rotates the imaging core; and conversion means to which a pulse signal corresponding to rotation of the imaging core is input and which converts a repetition frequency of the input pulse signal into a converted pulse signal in accordance with a set number of radially-aligned lines configuring one frame of the ultrasound tomographic image; characterized in that the imaging apparatus for diagnosis further comprises: means that generates a drive signal for the ultrasound transceiver so as to obtain the ultrasound tomographic image with the number of lines based on the converted pulse signal and that transmits the generated drive signal to the ultrasound transceiver via the motor drive unit; and generating means that determines a valid pulse in accordance with the number of lines from the converted pulse signal and that generates a pulse signal representing a timing of sampling of an optical coherence signal for generating the optical tomographic image having a pulse train selected, based on the valid pulse from a pulse signal representing a cycle of a light source generating light for interfering with light from the optical transceiver. means that generates a drive signal for the ultrasound transceiver so as to obtain the ultrasound tomographic image with the number of lines based on the converted pulse signal and that transmits the generated drive signal to the ultrasound transceiver via the motor drive unit; and generating means that determines a valid pulse in accordance with the number of lines from the converted pulse signal and that generates a pulse signal representing a timing of sampling of an optical coherence signal for generating the optical tomographic image having a pulse train selected, based on the valid pulse from a pulse signal representing a cycle of a light source generating light for interfering with light from the optical transceiver.