To provide a high-speed fluid device having a high-speed fluid machine such as a turbo-machine, a turbo-charger, or a blower built therein.

This high-speed fluid device comprises: a frictional roller step-up gear utilizing a wedge action having a low speed side shaft 3 having an outer ring fitted to one end part, a high speed side shaft rotatably supported on the low speed side shaft and an outer ring eccentrically to each other, at least one guide rollers 37a and 37b rotatably supported between the outer ring 32 and the high speed side shaft 17, and at least one movable roller 38; an electric motor 60 having a drive shaft 61 connected to the low speed side shaft; and the high-speed fluid machine 51 connected to the high speed side shaft and receiving a driving from the high speed side shaft.