Sankaku Channel/shako cap

A shako is a tall, cylindrical military cap, usually with a visor and sometimes tapered at the top. It is usually adorned with some kind of ornamental plate or badge on the front, metallic or otherwise, and often has a feather, plume, or pompom attached at the top. (from Wikipedia)

It's commonly seen in parade-grade military uniforms, marching bands and majorettes.