Provided is a flow meter capable of logging data more reliably. In this operation, a detection element repeatedly detects a physical quantity related to a flow rate of a fluid flowing in a pipe in a predetermined sampling cycle. Based on physical quantities, a calculation part sequentially calculates the flow rate of the fluid in the pipe. Further, a time measurement part calculates the time. A control storage part is caused to store a logging target, a logging cycle, and logging start definition information. Based on the logging start definition information, a control part automatically starts logging of the logging target in response to startup of the flow meter, and causes a log storage part to store the time measured by the time measurement part and a numerical value of the logging target in association with each other in every logging cycle.