Provided are a body cavity observation system, a trocar apparatus, and an operation method of body cavity observation system capable of performing a white balance in a body cavity.A trocar with camera 16 has a camera section 36. The camera section 36 obtains a trocar image that includes an image of a white part 94 on a surface of a puncture member 55 by performing imaging when the puncture member 55 of a trocar shaft 17 is exposed at a deployed position. A white balance setting section for trocar image 18a sets a white balance for the trocar image based on the image of the white part 94 in the trocar image.
