Air flow meter with reduced error due to backflow

The invention relates to an air flow meter which can decrease the error due to the backflow. Throttle valve (17) which opens and shuts the air intake passage (19) is installed in the air intake passage (19) of the internal combustion engine (1). The first sensor part (161) is installed in the air intake passage (19) in the upstream of throttle valve (17). Further, the second sensor part (141) is installed-in the air intake passage (19) in the downstream of throttle valve (17). Pulsation compensating means (671) corrects the pulsation of the air flowrate signal detected by the first sensor part (161) by using the output signals of the first and the second sensor parts (161, 141) based on each cylinder of the internal combustion engine (1).