A handheld type ultrasound diagnostic apparatus comprising: an ultrasound probe; and a diagnostic apparatus main body connected to the ultrasound probe, wherein the diagnostic apparatus main body includes: an image generation unit that generates an ultrasound image based on a reception signal acquired by using the ultrasound probe; a monitor with a touch sensor that displays the ultrasound image; a microphone for inputting a voice command; and a voice recognition unit that recognizes a voice command which is input via the microphone, wherein the diagnostic apparatus main body performs switching between a normal screen display mode and a full-screen display mode by performing a mode switching operation on the diagnostic apparatus main body or the ultrasound probe, the normal screen display mode being a mode in which the ultrasound image generated by the image generation unit and an operation panel for operating the ultrasound diagnostic apparatus are displayed on the monitor and an operation of the ultrasound diagnostic apparatus is performed via the operation panel, and the full-screen display mode being a mode in which only the ultrasound image generated by the image generation unit is displayed on the monitor and an operation of the ultrasound diagnostic apparatus by using a voice command is possible, and wherein a touch operation on a screen of the monitor is enabled in the normal screen display mode, and a touch operation on a screen of the monitor is disabled in the full-screen display mode. an ultrasound probe; and a diagnostic apparatus main body connected to the ultrasound probe, wherein the diagnostic apparatus main body includes: an image generation unit that generates an ultrasound image based on a reception signal acquired by using the ultrasound probe; a monitor with a touch sensor that displays the ultrasound image; a microphone for inputting a voice command; and a voice recognition unit that recognizes a voice command which is input via the microphone, an image generation unit that generates an ultrasound image based on a reception signal acquired by using the ultrasound probe; a monitor with a touch sensor that displays the ultrasound image; a microphone for inputting a voice command; and a voice recognition unit that recognizes a voice command which is input via the microphone, wherein the diagnostic apparatus main body performs switching between a normal screen display mode and a full-screen display mode by performing a mode switching operation on the diagnostic apparatus main body or the ultrasound probe, the normal screen display mode being a mode in which the ultrasound image generated by the image generation unit and an operation panel for operating the ultrasound diagnostic apparatus are displayed on the monitor and an operation of the ultrasound diagnostic apparatus is performed via the operation panel, and the full-screen display mode being a mode in which only the ultrasound image generated by the image generation unit is displayed on the monitor and an operation of the ultrasound diagnostic apparatus by using a voice command is possible, and wherein a touch operation on a screen of the monitor is enabled in the normal screen display mode, and a touch operation on a screen of the monitor is disabled in the full-screen display mode.