PURPOSE: To simplify a job for positioning as well as to prevent any displacement from occurring by installing a bearing, holding each slide plate in each direction orthogonal with the axial direction of an intake passage and the sliding direction of each of these slide plates, in a slide valve type throttle valve.

CONSTITUTION: In a slide valve S as a throttle valve, both first and second slide plates 2, 3 are set up in a slide valve body 1 up and down, in keeping a specified interval. When an accelerator pedal is operated, a throttle rod 13 and the second slide plate 3 as one body with the former are moved to the right. Simultaneously the first slide plate 2 is moved to the left via a lever 15. Accordingly, an area of a lapping part in both first and second plate hole parts 5, 6 is varied to some extent and interconnected to a throttle port 7. In this case, each of needle roller bearings 19 is installed in each spacing part 22 between both longitudinal surfaces of these first and second slide plates 2, 3 and the slide valve body 1.