A connection setting method, used in a camera system in which at least one camera head unit is connected to at least one camera control unit that controls the camera head unit via a single transmission network in order to connect the camera control unit includes: measuring delay of image data from the camera head unit to be connected; and determining a transmission rate at which image data is transmitted from the camera head unit to be connected. The determining is so carried out that when the delay is greater than a threshold corresponding to the amount of data smaller than or equal to a maximum amount of transmission over the network, the sum of the transmission rates at which image data transmitted over the network is smaller than or equal to the maximum amount of transmission over the network and image data having a higher preset priority is transmitted at a higher transmission rate.