An interface conversion apparatus (50; 70) to be provided in a mobile communication system that transmits data according to an industrial protocol, the interface conversion apparatus (50; 70) comprising: a communication quality measurement unit (123; 173) adapted to measure communication quality inside the mobile communication system; wherein the communication quality comprises a communication delay amount and a fluctuation amount which is a variation in the communication delay amount per packet; a storage unit (113; 163) adapted to store history information including a measurement result of the communication quality measured by the communication quality measurement unit (123; 173); an adjustment time determination unit (124; 174) adapted to: refer to evaluation index information specifying, for each communication group, a permitted priority, an allowable range of variation in the measurement result of the communication quality allowed (503, 504) and a fluctuation adjustment time for absorbing a fluctuation in an arrival time of a packet received; select a communication group having the permitted priority corresponding to priority information assigned to the packet acquired by a data communication unit (121, 171) of the interface conversion apparatus (50, 70); and determine whether the measurement result of the communication quality obtained from the history information satisfies the allowable range of variation in the measurement result of the communication quality allowed (503, 504) prescribed for the selected communication group; a communication group selection unit (125; 175) adapted to select the communication group corresponding to data identification information of the packet received after the selected communication group is determined; wherein the data identification information is acquired by the communication group selection unit (125; 175) from the packet received, and includes a communication protocol type and a data identifier; and a communication time adjustment unit (126; 176) adapted to control the packet received for each communication group in response to determining (YES in S17) that the communication delay amount and the fluctuation amount satisfy conditions prescribed for the selected communication group, using the fluctuation adjustment time in the evaluation index information corresponding to the communication group that is determined by the adjustment time determination unit (124; 174). a communication quality measurement unit (123; 173) adapted to measure communication quality inside the mobile communication system; wherein the communication quality comprises a communication delay amount and a fluctuation amount which is a variation in the communication delay amount per packet; a storage unit (113; 163) adapted to store history information including a measurement result of the communication quality measured by the communication quality measurement unit (123; 173); an adjustment time determination unit (124; 174) adapted to: refer to evaluation index information specifying, for each communication group, a permitted priority, an allowable range of variation in the measurement result of the communication quality allowed (503, 504) and a fluctuation adjustment time for absorbing a fluctuation in an arrival time of a packet received; select a communication group having the permitted priority corresponding to priority information assigned to the packet acquired by a data communication unit (121, 171) of the interface conversion apparatus (50, 70); and determine whether the measurement result of the communication quality obtained from the history information satisfies the allowable range of variation in the measurement result of the communication quality allowed (503, 504) prescribed for the selected communication group; a communication group selection unit (125; 175) adapted to select the communication group corresponding to data identification information of the packet received after the selected communication group is determined; wherein the data identification information is acquired by the communication group selection unit (125; 175) from the packet received, and includes a communication protocol type and a data identifier; and a communication time adjustment unit (126; 176) adapted to control the packet received for each communication group in response to determining (YES in S17) that the communication delay amount and the fluctuation amount satisfy conditions prescribed for the selected communication group, using the fluctuation adjustment time in the evaluation index information corresponding to the communication group that is determined by the adjustment time determination unit (124; 174).