Lobe mixer for jet flow

There is disclosed a lobe mixer comprising: a cylindrical partition wall 22 which partitions a high-speed inner flow from a low-speed outer flow; a lobe portion 24 which is disposed on a downstream side of the partition wall and whose transverse sectional shape is a waveform shape and is enlarged on the downstream side; and a connecting reinforcement member 26 which is disposed between lobe side walls 24a extending in a radial direction of the lobe portion to connect the adjacent lobe side walls to each other. The connecting reinforcement member 26 is a thin member disposed along a flow line of a fluid which flows between the lobe side walls.