This paper try to theoretically bring out the problems occurred when food safety signals, which are used safety standard or certification, are incompletely transmitted to buyers. Theoretical analysis of transaction game model without restriction for rational belief can explain following situations. Firstly, consumer attitude of untrustworthiness of food safety has a certain amount of rationality. Secondly, after strengthening of food sanitary inspection at upper stream of food distribution channel, the information of inspection results mislead harmful rumor. Thirdly, q excessively high or low belief of normal food spoils the effect of introducing food safety certification. Results indicate that food safety standard or certification needs proper belief control in applicable methods.