For the purpose of counting the number of cells within a culture container readily and accurately, a cell analysis device includes a cell-image acquiring unit that acquires an image of cells within a culture container in which the cells are cultured, a usability determining unit that determines whether or not the image acquired by the cell-image acquiring unit is usable, a number-of-cells counting unit that counts the number of cells within the image determined as being usable by the usability determining unit, and a number-of-cells calculating unit that calculates the number of cells within the culture container based on the number of cells counted by the number-of-cells counting unit.