The interviewer wants to know why you are leaving your current job because they want to understand your motivations for seeking a new opportunity. They may be trying to gauge whether you are leaving for positive reasons, such as career growth or a better work-life balance, or negative reasons, such as a toxic work environment or lack of job security. By understanding your reasons for leaving, the interviewer can better assess whether you will be a good fit for the new role and the company culture. It's important to be honest and tactful in your response, highlighting the positive aspects of your current job while explaining how the new opportunity aligns with your long-term career goals.