A measurement system and a measurement method that are capable of accurately measuring liquid fuel stored in a container. When the air pressure within a first container (3) is less than a predetermined pressure, air is supplied into the first container (3) through a first pipeline (13) by a pressure application means (6). Also, both the volume of the supplied air and a quantity of change in the air pressure within the first container (3) due to the air supply are detected or calculated, and the volume of the liquid fuel within the first container (3) is calculated from both the volume of the supplied air and the quantity of change in the air pressure. When the liquid fuel within a second container (4) is less than a predetermined quantity, a predetermined quantity of liquid fuel is fed from the first container (3) into said second container (4) through the second pipeline (12) by a feed means (8), and the volume of the liquid fuel within the first container (3) is calculated based on the number of times that the liquid fuel was fed. Therefore, a liquid fuel quantity supplied from the first container (3) into the second container (4) can be accurately grasped regardless of shape and tilt of the first container (3).