An endoscope system having a first image pickup device including at least one image pickup unit that is capable of picking up an image of an object, a second image pickup device including at least one image pickup unit, the second image pickup device being different from the first image pickup device, a retaining member being provided for retaining the second image pickup device in a body cavity, and including a camera cable that is connected to the second image pickup device and transmits an image pickup signal obtained by the second image pickup device, and a wire connected to the second image pickup device, a signal processing device that is provided outside the body cavity and processes image pickup signals obtained by the first image pickup device and the second image pickup device, and a display device that displays an image signal outputted from the signal processing device.