A train-information managing apparatus comprising: central apparatuses (1-1, 1-2) mounted on each car (TC1, TC2) at both ends of a formation of a train; terminal apparatuses (2-1 to 2-4) mounted on each intermediate car (M1-1, M1-2, M2-1, M2-2) of the formation; and a trunk transmission line that communicatively connects the central apparatuses (1-1, 1-2) and the terminal apparatuses (2-1 to 2-4), characterized in that when one of the central apparatuses (1-1; 1-2) transmits data including its own car information to the other central apparatus (1-2; 1-1) side at a fixed cycle via the trunk transmission line, only the first time after a start-up of the one central apparatus (1-1; 1-2), the one central apparatus (1-1; 1-2) gives first serial numbers (1 to M) including a plurality of numbers, order of which is specified in advance, to the data in order according to transmission order, gives, after all of the first serial numbers are used, second serial numbers (M+1 to N), including a plurality of numbers specified in the order and numbers later than the first serial numbers, to the data in order according to the transmission order, and returns, after the second serial numbers are used till a last number, to a first number of the second serial numbers again and gives the second serial numbers to the data in order, wherein when a serial number included in data received from the terminal apparatus (2-1 to 2-4) of an adjacent car on the one central apparatus (1-1; 1-2) side or from the one central apparatus (1-1; 1-2) is the first serial number and a serial number included in data received and stored last time is the second serial number, the terminal apparatuses (2-1 to 2-4) store the received data, and wherein when a serial number included in data received from the terminal apparatus of an adjacent car on the one central apparatus (1-1; 1-2) side is the first serial number and a serial number included in data received and stored last time is the second serial number, the other central apparatus (1-2; 1-1) stores the received data. central apparatuses (1-1, 1-2) mounted on each car (TC1, TC2) at both ends of a formation of a train; terminal apparatuses (2-1 to 2-4) mounted on each intermediate car (M1-1, M1-2, M2-1, M2-2) of the formation; and a trunk transmission line that communicatively connects the central apparatuses (1-1, 1-2) and the terminal apparatuses (2-1 to 2-4), characterized in that when one of the central apparatuses (1-1; 1-2) transmits data including its own car information to the other central apparatus (1-2; 1-1) side at a fixed cycle via the trunk transmission line, only the first time after a start-up of the one central apparatus (1-1; 1-2), the one central apparatus (1-1; 1-2) gives first serial numbers (1 to M) including a plurality of numbers, order of which is specified in advance, to the data in order according to transmission order, gives, after all of the first serial numbers are used, second serial numbers (M+1 to N), including a plurality of numbers specified in the order and numbers later than the first serial numbers, to the data in order according to the transmission order, and returns, after the second serial numbers are used till a last number, to a first number of the second serial numbers again and gives the second serial numbers to the data in order, wherein when a serial number included in data received from the terminal apparatus (2-1 to 2-4) of an adjacent car on the one central apparatus (1-1; 1-2) side or from the one central apparatus (1-1; 1-2) is the first serial number and a serial number included in data received and stored last time is the second serial number, the terminal apparatuses (2-1 to 2-4) store the received data, and wherein when a serial number included in data received from the terminal apparatus of an adjacent car on the one central apparatus (1-1; 1-2) side is the first serial number and a serial number included in data received and stored last time is the second serial number, the other central apparatus (1-2; 1-1) stores the received data.