We investigated the effect of cold plasma application on the yield and grain quality of rice (Oryza sativa L.), focusing on the brewer’s rice cultivar, Yamadanishiki. Two treatment methods were examined in a paddy; direct plasma irradiation of seedlings and indirect treatment with plasma-activated Ringer’s lactate solution (PAL) during the vegetative growth phase. Periodic direct irradiation for 30 s increased whole plant weight and grain yield. Treatment with PAL promoted some growth of panicles relatively and partially suppressed the growth of culms and leaves. Both treatments affected the grain quality; an increase of the ratio of white-core grains to total number of grains, which is suited for producing Japanese sake rice, as well as a decrease of the ratio of immature grains. The results showed that the effective production of rice grains for sake production can be improved by the application of cold plasma treatment of rice seedlings in a paddy. Highlight Rice plants of brewer’s rice cultivar in a paddy were treated with cold plasma, by the direct irradiation of plants and the immersed of plants in plasma-activated Ringer’s lactate (PAL). Direct plasma irradiation promoted plant weight, grain ripening, and increased yield. PAL treatment affected the growth of main stem and promoted the growth of panicles relatively. Both treatments improved the producing white-core grains, in addition to promotion of grain ripening. Cold plasma treatment can be applied to produce stable and high-quality food in various agriculture and food industries, which can achieve the sustainable developmental goals (SDGs).