A gas meter comprising: a flow rate measurement section, configured to measure a flow rate of gas flowing through a gas flow path, a flow rate computing section, configured to calculate flow rate data based on flow rate measurement values measured by said flow rate measurement section, a function setting section, configured to set security functions regarding a use of gas, a monitoring section, configured to monitor problems during the use of gas according to security functions including a set function having been set by said function setting section, a control section, configured to perform a processing of the security functions in the case that a problem is detected by said monitoring section, and a communication section, configured to communicate with a monitoring center for managing a supply of gas based on an instruction of said control section, wherein said function setting section being configured to receive security function information transmitted from said monitoring center via said communication section and to set a predetermined security function based on said security function information, and said control section being configured to shut off the supply of gas in the case that a phenomenon satisfying an operation condition of the set function having been set by said function setting section has occurred, the gas meter further comprises a security function information storage section configured to store the security function information received via said communication section wherein said function setting section being configured to select a desired security function information from a plurality of security function information stored in said security function information storage section, characterized in that said monitoring section being configured to have a first monitoring operation for monitoring the security functions set by the function setting section and to have a second monitoring operation for monitoring the security functions not set by the function setting section, and the control section being configured to shut off the supply of gas in the case that a phenomenon satisfying an operation condition of a security function set in the function setting section has been detected by the first monitoring operation of the monitoring section, while issuing a warning notice to the monitoring center in the case that a phenomenon satisfying an operation condition of a security function not set in the function setting section has been detected by the second monitoring operation of the monitoring section. a flow rate measurement section, configured to measure a flow rate of gas flowing through a gas flow path, a flow rate computing section, configured to calculate flow rate data based on flow rate measurement values measured by said flow rate measurement section, a function setting section, configured to set security functions regarding a use of gas, a monitoring section, configured to monitor problems during the use of gas according to security functions including a set function having been set by said function setting section, a control section, configured to perform a processing of the security functions in the case that a problem is detected by said monitoring section, and a communication section, configured to communicate with a monitoring center for managing a supply of gas based on an instruction of said control section, wherein said function setting section being configured to receive security function information transmitted from said monitoring center via said communication section and to set a predetermined security function based on said security function information, and said control section being configured to shut off the supply of gas in the case that a phenomenon satisfying an operation condition of the set function having been set by said function setting section has occurred, the gas meter further comprises a security function information storage section configured to store the security function information received via said communication section wherein said function setting section being configured to select a desired security function information from a plurality of security function information stored in said security function information storage section, characterized in that said monitoring section being configured to have a first monitoring operation for monitoring the security functions set by the function setting section and to have a second monitoring operation for monitoring the security functions not set by the function setting section, and the control section being configured to shut off the supply of gas in the case that a phenomenon satisfying an operation condition of a security function set in the function setting section has been detected by the first monitoring operation of the monitoring section, while issuing a warning notice to the monitoring center in the case that a phenomenon satisfying an operation condition of a security function not set in the function setting section has been detected by the second monitoring operation of the monitoring section.