The gel-covering apparatus has an inexpensive configuration that can supply the gelling agent to the seed covering portions under uniform pressure when performing simultaneously a plurality of same processes of covering the seeds with gelling agent. The gelling agent is supplied and filled into the closed spaces (73m) formed between the eight passages (73c) and the plungers (73h) in the nozzle block (73). The eight pressurizing air cylinders (77) connected to the eight gel supply passages (73B) communicating with the spaces (73m) are operated to pressurize the gelling agent in the spaces (73m) through the gel passages (75a) to cause the plungers (73h) in respective passages (73c) to move up, opening the valves (73b) at the lower ends of the passages (73c). At the same time, the seeds to be processed are thrown from above into the passages (73v) in the plungers (73h) so that the seeds falling from the lower ends of the passages (73v) down below the plungers (73h) are enclosed by the gelling agent, which is dropped from the spaces (73m) through the valves (73b) down below the passages (73c), to form gelling agent-covered seeds.