The safety aspect of building is the major component in building construction. One of the component aspect is the safety aspect of fire-risk. Fire is a disaster resulting loss and damage for many parties. The loss and damage are from material and non-material, or even loss of life. Based on the fire cases, a building is having the highest potential to be happened a fire. Many factors can cause a fire, such as human error and electrical error. This research is conducted to find out the reliability value on building safety system from a fire. The method of this research by using direct observation to components that will be assessed such as equipment, rescuing tool, active protection system and passive protection system based on the guidelines of checking system on safety building (Pd-T-11-C). The result of this study showed that the reliability value on building safety system is 79,5 %. based on the assessment of reliability system on safety building of Rusunawa Projotamansari 4 Bantul is categorized as moderate “C”