Disclosed are a pharmaceutical composition and a beauty-purposed pharmaceutical composition for prevention or treatment of neuromuscular disease, the composition including a combination of Erigeron annuus flower-based essential oil and Botox. Erigeron annuus flower-based essential oil inhibits t-SNARE protein and v-SNARE protein expression in neurons to inhibit the formation of SNARE protein complexes. Erigeron annuus flower-based essential oil inhibits the regeneration of t-SNARE protein and v-SNARE protein degraded by Botox to inhibit neurotransmitter release. Accordingly, an efficacy duration of Botox may be extended. Thus, Erigeron annuus flower-based essential oil may be usefully used in combination with Botox as Botox adjuvant for the prevention and treatment of neuromuscular disease or for beauty.