A kind of interference, called direct access interference, is found in the calculus of Mobile Resources(MR), which will cause more damage than the grave interference one finds in the calculus of Mobile Ambients,because in MR malicious environments or contexts can freely access the sensitive resources inside a process. This kind of interference should be regarded as a program error. To control the direct access interference, we devise a variant of MR, the calculus of Safe Mobile Resources (SR). The authors use a type system to avoid the occurrence of all direct access interferences. Due to the study, the grave interference is a special form of the direct access interference, which is also controlled in SR. At the end of the paper, several examples are provided to illustrate how to use the new calculus and how robust it is.