The present invention relates to a flow rate measurement device and, more specifically, to a flow rate measurement device and a flow rate measurement method, wherein a flow rate is measured by sensing a rotation caused by a flow of a fluid. The present invention provides a flow rate measurement device characterized by comprising: a housing (100) having a fluid inlet port (111) and a discharge port (112) formed to face each other; a rotating portion (200) comprising a rotating shaft (210) arranged perpendicularly to a virtual line (C) connecting the inlet port (111) and the discharge port (112) inside the housing (100), and a blade (220) rotated by a flow of a fluid around the rotating shaft (210); a sensor portion arranged to be spaced apart from the rotating shaft (210) in the radial direction of the rotating shaft (210) so as to sense the number of rotations of the rotating portion (200); and a control portion (330) for measuring the flow rate of the fluid on the basis of the number of rotations of the rotating portion (200) sensed by the sensor portion.