A fluid meter device comprising: a fluid passage unit including a plurality of measurement fluid passages (22a to 22c) provided in parallel; an inlet through which a fluid flows into the fluid passage unit; an outlet through which the fluid flows out of the fluid passage unit; wherein each of the measurement fluid passages (22a to 22c) comprises a flow rate value measuring unit (4a to 4c, 5a to 5c, 61a to 61c) configured to obtain information of a flow rate value of a fluid flowing through the measurement fluid passage (22a to 22c); and a main control unit; characterized in that: each of the measurement fluid passages (22a to 22c) comprises an auxiliary control unit (6a to 6c), wherein each of the auxiliary control units (6a to 6c) comprises - the flow rate measuring unit (4a to 4c, 5a to 5c, 61a to 61c); - a memory (62a to 62c) configured to store coefficient data (63a to 63c) corresponding to the measurement fluid passage (22a to 22c), and - a total flow value estimation unit (60a to 60c) configured to estimate a total flow value of the fluid flowed through the whole fluid passage unit based on the information of the flow rate value obtained by the flow rate value measuring unit (4a to 4c, 5a to 5c) and the coefficient data (63a to 63c) stored in the memory (62a to 62c); and each of the auxiliary control units (6a to 6c) is configured to send the estimated total flow value to the main control unit. a fluid passage unit including a plurality of measurement fluid passages (22a to 22c) provided in parallel; an inlet through which a fluid flows into the fluid passage unit; an outlet through which the fluid flows out of the fluid passage unit; wherein each of the measurement fluid passages (22a to 22c) comprises a flow rate value measuring unit (4a to 4c, 5a to 5c, 61a to 61c) configured to obtain information of a flow rate value of a fluid flowing through the measurement fluid passage (22a to 22c); and a main control unit; characterized in that: each of the measurement fluid passages (22a to 22c) comprises an auxiliary control unit (6a to 6c), wherein each of the auxiliary control units (6a to 6c) comprises - the flow rate measuring unit (4a to 4c, 5a to 5c, 61a to 61c); - a memory (62a to 62c) configured to store coefficient data (63a to 63c) corresponding to the measurement fluid passage (22a to 22c), and - a total flow value estimation unit (60a to 60c) configured to estimate a total flow value of the fluid flowed through the whole fluid passage unit based on the information of the flow rate value obtained by the flow rate value measuring unit (4a to 4c, 5a to 5c) and the coefficient data (63a to 63c) stored in the memory (62a to 62c); and each of the auxiliary control units (6a to 6c) is configured to send the estimated total flow value to the main control unit. each of the measurement fluid passages (22a to 22c) comprises an auxiliary control unit (6a to 6c), wherein each of the auxiliary control units (6a to 6c) comprises - the flow rate measuring unit (4a to 4c, 5a to 5c, 61a to 61c); - a memory (62a to 62c) configured to store coefficient data (63a to 63c) corresponding to the measurement fluid passage (22a to 22c), and - a total flow value estimation unit (60a to 60c) configured to estimate a total flow value of the fluid flowed through the whole fluid passage unit based on the information of the flow rate value obtained by the flow rate value measuring unit (4a to 4c, 5a to 5c) and the coefficient data (63a to 63c) stored in the memory (62a to 62c); and - the flow rate measuring unit (4a to 4c, 5a to 5c, 61a to 61c); - a memory (62a to 62c) configured to store coefficient data (63a to 63c) corresponding to the measurement fluid passage (22a to 22c), and - a total flow value estimation unit (60a to 60c) configured to estimate a total flow value of the fluid flowed through the whole fluid passage unit based on the information of the flow rate value obtained by the flow rate value measuring unit (4a to 4c, 5a to 5c) and the coefficient data (63a to 63c) stored in the memory (62a to 62c); and each of the auxiliary control units (6a to 6c) is configured to send the estimated total flow value to the main control unit.