A medical device system includes a first medical device, a first memory corresponding to the first medical device, a second medical device, and a second memory corresponding to the second medical device, wherein the first memory includes a first shared area corresponding to the first medical device and a second shared area corresponding to the second medical device, the second memory includes a third shared area corresponding to the first medical device and a fourth shared area corresponding to the second medical device, the first medical device includes a first writing unit that dynamically writes, into a certain area included in the first shared area, definition data that defines a method for using the certain area and data corresponding to the definition data, and the second medical device includes a second writing unit that dynamically writes, into a certain area included in the fourth shared area, definition data that defines a method for using the certain area and data corresponding to the definition data.
