A fluorescent dye/probe that can rapidly identify the presence of disease is efficiently applied in a living organism and optically detected to obtain clear fluorescent images. There is provided an endoscope system comprising agent dispensing means for dispensing towards an acquisition object a fluorescent agent that binds with a specific substance inside the acquisition object or that accumulates inside the acquisition object control means for controlling the agent-dispensing means a light source portion for emitting excitation light for exciting the fluorescent agent and irradiation light having different spectral characteristics from the excitation light an optical system for transmitting the excitation light and the irradiation light towards the acquisition object and image-acquisition means, disposed at a portion that is inserted inside a body cavity and capable of acquiring fluorescence excited from the acquisition object by the excitation light, and light in a different wavelength band, which is excited from the acquisition object by the irradiation light wherein the control means controls the agent-dispensing means so that the acquisition object is irradiated with the irradiation light before the fluorescent agent is spouted out towards the acquisition object.
