Tomatoes are an important commodity for both domestic and foreign needs. In Indonesia, tomatoes play an important role both need, people consume as fruit or to complete the ingredient in cooking. Therefore, maintaining the fertility of tomato plants is very important, so that tomato production continues to increase in Indonesia. The decrease in tomato production due to pest attack is an important problem in tomato plant care. In this work, a disease detection system in tomato plants will be developed using an intelligent system technique. The system involved image processing and intelligent technique. The system recognizes the kind of disease of the tomato plant based on the feature of the tomato leaf. Tomato plant disease detection system based on the leaf of tomato processing by image procession technique and Convolution Neural Network (CNN). The system is working properly, since it resulting the training and testing accuracy of 98% and 95%, respectively.