Penelitian ini bertujuan untuk mengetahui pengaruh Kredibilitas Sumber Influencer Media Sosial pada Akun Instagram Tasya Farasya terhadap Sikap Merek Kosmetik Make Over di JABODETABEK dan menentukan dimensi Kredibilitas Sumber yang memiliki pengaruh paling besar terhadap Sikap Merek. Jenis penelitian yang digunakan adalah explanatory dengan pendekatan kuantitatif, menggunakan kuesioner berupa Google Form dan dianalisis menggunakan analisis regresi berganda. Dalam pengambilan sampel peneliti menggunakan teknik non probability sampling dengan teknik purposive sampling. Kriteria sampel dalam penelitian ini adalah: (1) Wanita pengguna media sosial Instagram berusia 18-35 tahun yang berdomisili di JABODETABEK, (2) Mengetahui Influencer Media Sosial Tasya Farasya, (3) Mengetahui Merek kosmetik Make Over, (4) Pernah mengunjungi akun Instagram Tasya Farasya lebih dari satu kali, dan (5) Pernah melihat konten promosi Tasya Farasya dengan brand kosmetik Make Over di Instagram. Hasil penelitian menunjukkan bahwa kredibilitas social media influencer berpengaruh terhadap sikap konsumen terhadap merek, dimana dimensi trustworthiness merupakan dimensi yang paling besar pengaruhnya terhadap pembentukan sikap terhadap merek. Hasil penelitian merekomendasikan jika ingin mencari endorser lain, Make Over perlu memilih seseorang dengan kredibilitas yang baik, terutama seseorang yang dapat dipercaya.

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This study aims to determine the effect of Social Media Influencer Source Credibility on Tasya Farasya's Instagram Account on Make Over Cosmetic Brand Attitudes in JABODETABEK and determine the Source Credibility dimension which has the greatest influence on Brand Attitude. The type of research used is explanatory with a quantitative approach, using a questionnaire in the form of Google Form and analyzed using multiple regression analysis. In taking the sample, the researcher used a non-probability sampling technique with a purposive sampling technique. The sample criteria in this study are: (1) Female Instagram social media users aged 18-35 years who live in JABODETABEK, (2) Knowing Tasya Farasya Social Media Influencers, (3) Knowing Make Over cosmetic brands, (4) Ever visited accounts Tasya Farasya's Instagram more than once, and (5) Ever seen Tasya Farasya's promotional content with the Make Over cosmetic brand on Instagram. The results show that the credibility of social media influencers has an effect on consumer attitudes towards brands, where the dimension of trustworthiness is the dimension that has the greatest influence on the formation of attitudes towards brands. The results of the study recommend that if you want to find another endorser, Make Over needs to choose someone with good credibility, especially someone who can be trusted.