A diagnosis support device includes a control unit that correlates a plurality of pixels included in a two-dimensional image with two or more classes including a biological tissue class, the two-dimensional image being generated by using a signal of a reflected wave of ultrasound transmitted inside a biological tissue through which blood passes and the two-dimensional image including the biological tissue, generates a three-dimensional image of the biological tissue from a pixel group correlated with the biological tissue class, and performs control of displaying the generated three-dimensional image of the biological tissue.