A gaming system includes a plurality of gaming machines and a control device connected to the gaming machines. Each of the gaming machines has: a display device, which displays a plurality of symbols; a controller, which performs a process of rearranging symbols arranged on the display devices after gaming mediums are betted, and thereafter, executing a base game in which a payment is made in accordance with the rearranged symbols; and a communication interface, which transmits information pertinent to the betted gaming mediums to the control device, together with information for identifying a transmission source. The control device has: a memory, which stores identification information for identifying a gaming machine participated in a common game executed simultaneously in groups and identification information for identifying a group to which the gaming machine belongs in association with each other; a communication interface, which receives information transmitted from each of the gaming machines; and a controller, which executes a process of specifying a group to which a transmission source of information received by the communication interface, based upon the information stored in the memory and a process of accumulatively summing up a reserved amount by the specified group, and then, storing the sum in the memory in order to reserve part of the gaming mediums betted at the gaming machine as the transmission source in groups to which the gaming machines belong.