A design support device includes an operation reception unit that receives an operation from a user, a program creation unit that creates a ladder program in accordance with the operation received by the operation reception unit, and a circuit block extraction unit that extracts a circuit block from the ladder program when the circuit block is formed and a predetermined condition is satisfied. The circuit block is formed by detecting that one end of a circuit including a plurality of program elements is connected to one of two power rails included in the ladder program and that another end of the circuit is connected to another one of the two power rails. Further, there is a circuit block memory that stores configuration information of the circuit block extracted by the circuit block extraction unit. There is also a notification unit.