Blowing unit, drying device, liquid applying system, and printing system

Provided are a blowing unit, a drying device, a liquid applying system, and a printing system with which it is possible to realize uniformly blowing air via a plurality of jetting ports.In a blowing unit that has a hollow structure and blows air via a plurality of jetting ports disposed at a first surface, a gas inflow port through which a gas supplied from a gas supply source flows in is formed in a second surface which intersects the first surface and at which the jetting ports are not disposed and a ratio of a sum of opening areas of the plurality of jetting ports to an opening area of the gas inflow port is equal to or larger than 0.1 and equal to or smaller than 1.0.