There is provided an excellent biological signal monitor device that allows a living tissue moving in accordance with a body motion or a vibration to be observed as if it were standing still. A reverse correction processing unit (114) subjects a B-mode image to reverse correction based on a movement amount of the living tissue detected by a movement amount detection unit (113), and outputs the B-mode image corresponding to the living tissue moving in accordance with a body motion as quasi-still image information. An arithmetic processing unit (115) subjects the quasi-still image information from the reverse correction processing unit (114) to arithmetic processing such as averaging and filter processing, so as to remove a random noise component. As a result, it is possible to display, for example, a contour portion of a blood vessel wall as the living tissue clearly.
