A flow meter device for measuring flows of a gas flowing into a plurality of gas instruments including a fuel cell, comprising: a fluid passage in which the gas flows; a flow measuring section for measuring a gas flow in the fluid passage; a determination flow data storage section for storing time series set data of the gas flow as determination flow data, for respective kinds of the plurality of gas instruments; and a gas instrument determiner section; wherein the gas instrument determiner section compares the time series set data of actual measurement values of the gas flow obtained in a first determination operation period to the determination flow data and determines whether the gas instrument in use is a fuel cell or a general gas instrument other than the fuel cell; wherein the first determination operation period which is a period from a time point when inflowing of the gas starts until a predetermined time lapses, and a second determination operation period which is a period which ends after the first determination operation period ends are set as periods in which the gas instrument determiner section is allowed to perform a determination operation; characterized in that: only if the gas instrument determiner section determines that there is a possibility that the gas instrument in use is the fuel cell or determines that the gas instrument in use is not the general gas instrument, the gas instrument determiner section shifts from the first determination operation period to the second determination operation period; and in that the gas instrument determiner section compares the time series set data of the actual measurement values of the gas flow obtained in the second determination operation period to the determination flow data and determines whether or not the gas instrument in use is the fuel cell. a fluid passage in which the gas flows; a flow measuring section for measuring a gas flow in the fluid passage; a determination flow data storage section for storing time series set data of the gas flow as determination flow data, for respective kinds of the plurality of gas instruments; and a gas instrument determiner section; wherein the gas instrument determiner section compares the time series set data of actual measurement values of the gas flow obtained in a first determination operation period to the determination flow data and determines whether the gas instrument in use is a fuel cell or a general gas instrument other than the fuel cell; wherein the first determination operation period which is a period from a time point when inflowing of the gas starts until a predetermined time lapses, and a second determination operation period which is a period which ends after the first determination operation period ends are set as periods in which the gas instrument determiner section is allowed to perform a determination operation; characterized in that: only if the gas instrument determiner section determines that there is a possibility that the gas instrument in use is the fuel cell or determines that the gas instrument in use is not the general gas instrument, the gas instrument determiner section shifts from the first determination operation period to the second determination operation period; and in that the gas instrument determiner section compares the time series set data of the actual measurement values of the gas flow obtained in the second determination operation period to the determination flow data and determines whether or not the gas instrument in use is the fuel cell.