An analyzing device includes a flow path plate having a flow path, through which a liquid flows, shaped like a rectangle, and having a light permeability, a light emitting unit having a light emitting lens and emitting light, and a light receiving unit including a light receiving lens and receiving the light, the analyzing device analyzing the liquid flowing inside the flow path plate, wherein the flow path plate has a pair of cutouts formed at an end face so as to face each other through a part of the flow path, wherein the pair of cutouts includes a first cutout in which the light emitting unit is disposed and a second cutout in which the light receiving unit is disposed.