To provide a better service for a customer using fewer persons by informing conditions of a metering machine by means of a lamp, voice, etc., to simply monitor the condition of the metering machine during supply of oil.

In order to develop an interface interconnecting a metering machine 2 and a metering machine monitoring device 1, oil feed conditions of the metering machine 2 such as metering machine waiting, temporary suspension of oil feed during oil feed, completion of oil feed can be monitored by means of lamps and voice utilizing a POS interface in the machine 2 in relation to installation cost. Monitoring can be conducted by a method wherein even a metering machine including no interface, which can change the time, can monitor, by monitoring time period by means of a timer to check temporary suspension of oil feed.