An ultrasonic diagnostic apparatus includes a main body, multiple caster modules configured to enable the main body to move, and a power transmission device. Each of the caster modules includes a wheel bracket, a wheel attached to the wheel bracket to be in contact with a ground, and a lever laterally and rotatably mounted to a top of the wheel bracket in order to change modes of the caster modules. The power transmission device transmits external force to the caster modules in order to change the modes of the caster modules, and includes a connection bar connecting levers to each other and configured to move laterally by the external force, a cam member having a cam surface and configured to rotate by the external force, a rolling member configured to move along the cam surface, and an elastic member configured to elastically bias the rolling member toward the cam surface.
