Perkembangan Internet dan perangkat telepon pintar secara langsung dapat mempengaruhi masyarakat dalam menggunakan media sosial. Peningkatan pengguna media sosial dapat dimanfaatkan oleh Usaha Mikro Kecil dan Menengah (UMKM). Instagram sebagai platform komplementer dari e-marketplace berpeluang besar dalam meningkatkan pendapatan UMKM. Pada kenyataannya, di Indonesia Instagram for Business belum secara efektif digunakan oleh UMKM. Penelitian ini membangun model adopsi Instagram for Business berdasarkan model Stimulus-Organism-Response (S-O-R) oleh UMKM. Metodologi penelitian menggunakan kuantitatif dan kualitatif (mixed methods), data kuantitatif dikumpulkan melalui kuesioner kepada UMKM dan pembelinya di Instagram. Data kualitatif diperoleh melalui wawancara dengan dengan beberapa UMKM. Model S-O-R digunakan pada penelitian sebelumnya mengenai impulse buying di Facebook. Pada penelitian ini model S-O-R dikembangkan untuk menganalisis response dari stimulus, berupa impulse buying, kepada UMKM dan pembelinya, yang dianggap sebagai organism. Data responden yang terkumpul diolah menggunakan SmartPLS 3. Hasil dari pengujian model S-O-R menunjukkan bahwa respon impulse buying dari sudut pandang UMKM hanya dipengaruhi oleh stimulus yang memiliki pengaruh positif secara langsung pada perceived usefulness yaitu product availability, ease of use, visual appeal dan advertisement content yang berdampak pada adopsi serta impulse buying. Apabila dari sudut pandang pembeli, keseluruhan stimulus tersebut memiliki pengaruh positif terhadap perceived usefulness dan perceived enjoyment yang mengestimasi respon perilaku impulsif dari pembeli.

---

The development of the Internet and smartphone devices can directly influence the public in using social media. Increased social media users can be utilized by Micro, Small and Medium Enterprises (MSMEs). Instagram as a complementary platform of e-marketplace has a great opportunity to increase MSME income. But in reality, MSMEs in Indonesia have not used Instagram for Business effectively. This study builds an Instagram for Business adoption model based on the Stimulus-Organism-Response (S-O-R) model by MSMEs. The research methodology uses quantitative and qualitative methods (mixed methods), quantitative data collected through questionnaires to MSMEs and buyers on Instagram. While qualitative data is obtained through interviews with several MSMEs. The S-O-R model was used in previous studies regarding impulse buying on Facebook. In this study the S-O-R model was developed to analyze responses from stimulus, in the form of impulse buying, to MSMEs and buyers, which are considered as organisms. The collected respondents' data were processed using SmartPLS 3. The results of the SOR model testing showed that the impulse buying response from the perspective of MSMEs was only influenced by stimuli that had a direct positive influence on perceived usefulness, namely product availability, ease of use, visual appeal and advertisement content have an impact on adoption and impulse buying. Whereas from the buyer's point of view, the overall stimulus has a positive influence on perceived usefulness and perceived enjoyment. Thus causing a response to impulsive behavior from buyers.