An analysis device includes a controller configured to count a pulse derived from a particles as a plural particles when a light reception level signal includes the pulse having a first extreme value point, a second extreme value point, and a third extreme value point, and the pulse fulfils a condition in which the third extreme value point is present between the first extreme value point and the second extreme value point in a pulse width direction of the pulse, the third extreme value point is present between the first extreme value point and a threshold in a pulse amplitude direction, the first extreme value point and the second extreme value point are each an extreme value point of a waveform projecting in a common direction, and the third extreme value point is an extreme value point of a waveform in a direction opposite to the common direction.