Penelitian ini bertujuan untuk mengimplementasikan dan mengevaluasi performa model deep learning Convolutional Neural Network (CNN) berbasis arsitektur ResNet-50 dalam klasifikasi citra Magnetic Resonance Imaging (MRI) tiga jenis tumor otak: glioma, meningioma, dan pituitary. Pendekatan transfer learning digunakan dengan dua skenario fine-tuning, yaitu pembekuan 30 layer pertama dan pembekuan 15 layer pertama. Dataset terdiri dari 3.064 citra MRI yang dibagi ke dalam data latih dan uji dengan rasio 80:20. Citra diproses melalui tahapan resizing, normalisasi, dan augmentasi untuk meningkatkan variasi data. Model dievaluasi menggunakan metrik akurasi, precision, recall, F1-score, confusion matrix, dan ROC-AUC. Hasil menunjukkan bahwa model dengan freeze 15 layer memberikan akurasi lebih tinggi sebesar 91,86% dibandingkan freeze 30 layer sebesar 90,88%. Namun, model dengan freeze 30 layer menunjukkan kestabilan dan generalisasi yang lebih baik terhadap data uji, terutama dalam mendeteksi meningioma. Temuan ini menunjukkan bahwa ResNet-50 efektif dalam klasifikasi tumor otak berbasis MRI, dan fine-tuning yang tepat berpengaruh terhadap performa akhir model.This study aims to implement and evaluate the performance of a deep learning Convolutional Neural Network (CNN) model based on the ResNet-50 architecture for classifying Magnetic Resonance Imaging (MRI) brain tumor images into three types: glioma, meningioma, and pituitary. A transfer learning approach was applied using two fine-tuning scenarios: freezing the first 30 layers and freezing the first 15 layers. The dataset consisted of 3,064 MRI images, split into training and testing data at an 80:20 ratio. Images were processed through resizing, normalization, and augmentation to enhance data diversity. The model was evaluated using accuracy, precision, recall, F1-score, confusion matrix, and ROC-AUC metrics. Results showed that the 15-layer freeze model achieved a higher accuracy of 91.86% compared to the 30-layer freeze model at 90.88%. However, the 30-layer freeze model demonstrated better stability and generalization on the test data, particularly in detecting meningioma. These findings indicate that ResNet-50 is effective for MRI-based brain tumor classification, and proper fine-tuning significantly influences model performance.