This paper points out the problem that existing Parameter-Efficient Fine-Tuning (PEFT) methods have limitations in improving performance because they freeze pre-learned weights and learn new low-rank or sparse weights. Since existing methods learn new weights from scratch, performance degradation occurs. VectorFit proposes a new parameterization method that adaptively learns the singular vectors and biases of W by utilizing the information inherent in the pre-learned weights W. Through this, we achieve performance similar to full fine-tuning with far fewer parameters (9x reduction) than existing PEFT methods, and experimentally demonstrate that our method performs superiorly in various tasks such as natural language understanding and generation, question answering, and image classification and generation through 19 datasets.