A liquid chromatograph that accurately detects, with a weight sensor, a remaining amount of a mobile phase during analysis and also an operation onto a system such as whether or not a container has been placed and whether or not the mobile phase has been added is provided. A container stores a mobile phase. A sensor detects a weight of the container in which the mobile phase is stored. A filter smoothens a signal output from the sensor and outputs the smoothened signal. A calculator calculates a liquid amount of the mobile phase stored in the container based on the signal output from the filter. When variation per unit time of the signal output from the sensor is larger than a prescribed threshold value, the filter has a smaller time constant for smoothening than when variation is smaller than the threshold value.