Disclosed is an intravital observation device that has a simple structure and that can observe a foreign material and both blood vessels of an artery and a vein inside a living body without requiring an angiographic agent, X-rays, or harming the body. The intravital observation device comprises a light source that irradiates light having a wavelength peak in a wavelength region of 800 to 1000 nm onto the living body and an imaging device that outputs an image data obtained by receiving the light that has passed through the living body. The imaging device is a digital camera whose minimum detection light amount per output at a time when receiving the light of 0.4 to 10 μW is less than or equal to 0.055 μW/bit.