The prevalence of food allergy (FA) is increasing, and there is an urgent need to take effective measures against it. One important measure is the avoidance diet, which shows a disadvantage, especially in case of accidental exposure. Oral tolerance restoration sheds new light on the control of FA. Oral tolerance is naturally a state of systemic unresponsiveness of the gastrointestinal tract to food antigens and its restoration can be a clinical therapy for FA. Its immune basis lies on the intestinal mucosal immune system and factors, such as gut microbiota and food processing methods, are also important. This review presents recent advances in oral tolerance and its closely related factors.