In order to provide technology for limiting the deterioration of hardware in a portable diagnostic ultrasound apparatus without increasing user workload, internal processing of the portable diagnostic ultrasound apparatus is controlled according to the opening or closing of the cover case in which the monitor is disposed. In particular, when the cover case is closed, not only is output of ultrasonic waves stopped but processing that is being executed inside the apparatus is appropriately terminated and the power is turned off. When so doing, processing that is being executed is interrupted and cancelled and processing that is waiting to be executed is cancelled. The cancelled information is stored in a storage device.
