Intake-air mass measuring apparatus for internal combustion engine

The invention relates to an intake-air measuring apparatus for an internal combustion engine, enabling to calculate a mass of intake-air inducted into the internal combustion engine, with a small map but at high accuracy, comprises: a means (11) for measuring out an air mass passing through a throttle valve (23) based on pressure in up/down streams of the throttle valve (23) and temperature in the upstream of the throttle valve (23); a means (12) for calculating an air mass passing through the intake valve (29) based on a rotation speed of the internal combustion engine, an open/close timing of the intake valve (29) and an opening of an EGR valve (24); and a means (13) for selecting either one of the air mass passing through the throttle valve (23) or the air mass passing through the intake valve (29), depending upon operation condition of the internal combustion engine, thereby outputting the selected air mass as inducted air mass into the internal combustion engine.