Real-world image super-resolution deals with complex and unknown degradations, making it challenging to produce plausible results in a single step. In this work, we propose a transformer model with an iterative generation process that iteratively refines the results based on predicted confidences. It allows the model to focus on regions with low confidences and generate more confident and accurate results. Specifically, our model learns to predict the visual tokens of the high-resolution image and their corresponding confidence scores, conditioned on the low-resolution image. By keeping only the most confident tokens at each iteration and re-predicting the other tokens in the next iteration, our model generates all high-resolution tokens within a few steps. To ensure consistency with the low-resolution input image, we further propose a conditional controlling module that utilizes the low-resolution image to control the decoding process from high-resolution tokens to image pixels. Experiments demonstrate that our model achieves state-of-the-art performance on real-world datasets while requiring fewer iteration steps compared to recent diffusion models.