A fire monitoring system includes a smoke detector, a first correction unit obtaining a first corrected value by multiplying a difference value between a reference value and a detection value by a first correction coefficient, a first conversion unit converting the first corrected value into a first smoke density, and a fire determination unit determining occurrence of a fire event based on the first smoke density. The first correction coefficient is set on an increase side corresponding to an increase in a rate of change of the reference value to an initial reference value, and an upper limit value is set for the first correction coefficient.