A safety system according to one or more embodiments including a safety controller that executes a safety program. The safety system includes: a collection unit configured to collect an input value over a predetermined period, the input value being a value of an input signal selected previously in one or a plurality of input signals input to the safety controller; and a visualization unit configured to reproduce a behavior of the safety program over the predetermined period based on the input value collected over the predetermined period, and to express visually an operating state of the safety program at an appointed point of time in the predetermined period.