An ultrasonic device unit includes an ultrasonic device including 1-st through n-th vibrator elements and 1-st through n-th device-side terminals connected corresponding respectively to the vibrator elements, and a flexible printed wiring board to be connected to the ultrasonic device, in which the flexible printed wiring board includes a first connector section provided with 1-st through k-th external connection terminals, a second connector section provided with (k+1)-th through n-th external connection terminals, a device connection section which is disposed between the first connector section and the second connector section, and to which the 1-st through n-th device-side terminals are connected, and interconnections adapted to connect the i-th device-side terminal and the i-th external connection terminal to each other.