A stop seal for application of high temperature and high pressure is disclosed. A stop seal contains a first seal member and a second seal member, wherein the stop seal can prevent a fluid of high temperature and high pressure from leaking into an atmospheric space because, when the fluid of high temperature is introduced and the first seal member is moved toward a direction adjacent to a pump shaft, an opposite side of the second seal member is moved from a first position to a second position by the first seal member so as to block a gap between a pump side and a housing.