A radiation imaging system comprising: a radiation imaging apparatus; an image processing apparatus (111, 229) configured to process an image obtained by the radiation imaging apparatus; a synchronous access point (115, 222) comprising a wireless communication means for connecting the radiation imaging apparatus to a wireless LAN, the access point (115, 222) being configured to communicate with a radiation controller and with the image processing apparatus (111, 229); and an entry apparatus (116, 223) which is associated with a radiation generator communicating with the radiation controller and which comprises a close proximity wireless communication means having a shorter communication range than the wireless communication means; said radiation imaging apparatus comprising: a first wireless communication means for communicating with the close proximity wireless communication means of the entry apparatus, and for receiving a communication parameter of a wireless LAN, the communication parameter being for connecting said radiation imaging apparatus to said wireless LAN; and a second wireless communication means for establishing a wireless LAN communication with the wireless communication means of the access point (115, 222), based on the communication parameter received by the first wireless communication means; wherein the radiation controller is configured, when the second wireless communication means of the radiation imaging apparatus communicates with the wireless communication means of the access point, to perform control to synchronize driving of said radiation imaging apparatus with emission of radiation from the radiation generator, wherein the image processing apparatus (111,229) is configured to connect to a backbone network (112, 229) and to connect the access point (115, 222), wherein the entry apparatus (116, 223) having the close proximity wireless communication means is configured to connect to the image processing apparatus (111, 229) by a wired connection (117,227), wherein the first wireless communication means of said radiation imaging apparatus is configured to receive the communication parameter of the wireless LAN from the image processing apparatus (111,229) via the entry apparatus (116, 223) in response to a press of an input means of said radiation imaging apparatus, wherein the second wireless communication means of said radiation imaging apparatus is configured to establish the wireless LAN communication with the access point (115, 222) based on the communication parameter received by the first wireless communication means, and wherein said radiation imaging apparatus is configured to perform a radiographic imaging in synchronization with the radiation generator (106, 225) using the wireless LAN communication established with the access point (115, 222). a radiation imaging apparatus; an image processing apparatus (111, 229) configured to process an image obtained by the radiation imaging apparatus; a synchronous access point (115, 222) comprising a wireless communication means for connecting the radiation imaging apparatus to a wireless LAN, the access point (115, 222) being configured to communicate with a radiation controller and with the image processing apparatus (111, 229); and an entry apparatus (116, 223) which is associated with a radiation generator communicating with the radiation controller and which comprises a close proximity wireless communication means having a shorter communication range than the wireless communication means; a first wireless communication means for communicating with the close proximity wireless communication means of the entry apparatus, and for receiving a communication parameter of a wireless LAN, the communication parameter being for connecting said radiation imaging apparatus to said wireless LAN; and a second wireless communication means for establishing a wireless LAN communication with the wireless communication means of the access point (115, 222), based on the communication parameter received by the first wireless communication means;