Trichophyton rubrum is the most common dermatophytosis etiology. The antifungal agent has several problems such as fungal resistance and therapy side effects. Cacao (Theobroma cocoa L.) bean shells extract contained flavonoids, alkaloids, and saponins which have an antifungal effect. This study aimed to test the in vitro cacao bean shells extract antifungal (especially: Trichophyton rubrum) effectiveness by agar well diffusion method. This was an experimental study with a post-test only control group design. This study used cacao bean shells extract concentration 25%, 50%, 75%, and 100%, ketokonazol as positive control, and aquadest as negative control. The average inhibition diameter of 25%, 50%, 75% and 100% cacao bean shells extract concentration were 10.65 mm, 18 mm, 26.92 mm, and 37.22 mm, respectively, while the ketoconazole inhibition diameter was 51.52 mm. Data were analyzed using the Kruskal-Wallis test and post hoc with Mann-Whitney. The results showed significant differences between each treatment group (p0.05). Cacao bean shells extract had an antifungal effect in inhibiting the growth of Tricophyton rubrum invitro.Keywords: Trichophyton rubrum, Cacao Bean Shells, Antifungal, Agar Well Diffusion Method, ABSTRAKTrichophyton rubrum adalah penyebab paling umum dermatofitosis. Obat dermatofitosis (antijamur) memiliki beberapa masalah seperti resistensi dan efek samping terapi. Ekstrak cangkang biji kakao (Theobroma cocoa L.) mengandung flavonoid, alkaloid, dan saponin yang memiliki efek antijamur. Tujuan penelitian ini untuk menguji efektivitas antijamur (khususnya Trichophyton rubrum) ekstrak cangkang biji kakao secara in vitro dengan metode difusi agar. Penelitian ini merupakan penelitian eksperimental dengan post-test only control group design. Penelitian ini menggunakan konsentrasi ekstrak cankang biji kakao 25%, 50%, 75%, dan 100%, ketokonazol sebagai kontrol positif, dan aquadest sebagai kontrol negatif. Rata-rata diameter hambat konsentrasi 25%, 50%, 75% dan 100% secara berturut-turut yaitu: 10,65 mm, 18 mm, 26,92 mm, dan 37,22 mm, sedangkan daya hambat ketoconazole adalah 51,52 mm. Data dianalisis menggunakan uji Kruskal-Wallis dan post hoc dengan Mann-Whitney. Hasil penelitian menunjukkan perbedaan yang signifikan antara masing-masing kelompok perlakuan (p 0,05). Ekstrak cangkang biji kakao memiliki efek antijamur dalam menghambat pertumbuhan Tricophyton rubrum invitro.Kata kunci: Trichophyton rubrum, Anti-jamur, Cangkang Biji Kaka, Metode Difusi Sumuran Agar