To provide a moving blade variable mechanism in an moving blade variable axial flow fan, which can transmit moving blade opening command from a moving blade drive unit directly to a transmission shaft without intervening a servo mechanism.

In a moving blade variable mechanism, a moving blade drive unit 1 transmits a moving blade opening command with a relatively small shaft torque to a linkage gear 3 through a worm gear 2 as a comparatively large shaft torque. The moving blade opening command is converted to axial linear displacement of a connecting rod 5 through a link 4. An outer thrust pad pressor 6, an inner thrust pad pressor 7 and a thrust pad 8 respectively inregrated with the connecting rod 5 are axialy and linearly displaced together with the connecting rod 5. The operation is transmitted to a thrust collar 9. Linear displacement of the thrust collar 9 is converted into rotary displacement through a rectangular slip liner 12 and an arm 13, for adjusting an opening angle of a moving blade 14.