The invention provides a chain breaking safety protection device for a high-altitude elevator for building. The chain breaking safety protection device comprises an elevator stand column, channel steel, a mounting plate and a sliding sash, wherein the channel steel is fixedly arranged on one side of the elevator stand column, and the sliding sash is fixedly arranged in the inner part of the mounting plate through a bearing rod; one side of the sliding sash is welded with a limiting block supporting rod, and a limiting block is arranged at one end of the limiting block supporting rod; and a locking block is arranged on the other side of the limiting block through a movable pin shaft. A lock head of the locking block is pushed to enter into a locking slot in the inner part of the channel steel through the movement of the internal structure of the sliding sash, so that a material bearing frame can be effectively prevented from continuously sliding during chain breaking. A negative pole patch is arranged in the inner part of the locking slot, and a positive pole patch is arranged in the inner part of the lock head, so that when the positive pole patch attaches to the negative pole patch, a user can be effectively reminded that a chain of the device is broken. By the arrangement of a series of structures, the device has the characteristics of good protection performance, conveniencein use, simple structure, etc.