In order to provide an ATM cell□packet switch which can easily maintain the band for the normality confirmation packet of the user data transfer path without influencing the user band at a state of in□band, and a communication control method using the switch, at least provided in the switch are: an SDRAM for storing the user data; a normality confirmation packet generator; a timing generator for generating the timing of a refresh cycle of the SDRAM; a selector for transferring the normality confirmation packet at the time of the refresh; and a packet reception unit for extracting the packet identifying information from the received packet data, and comparing the normality confirmation packet directly received from the packet generator to the normality confirmation packet received via the switch unit thereby to confirm the normality when the packet data is the normality confirmation packet.