A ladder diagram program generation assistance device, comprising: an input unit, configured to receive an input related to generation and editing of a ladder diagram program; a partial circuit search unit configured to, when the input unit receives a command name of function blocks related to a ladder circuit to be inserted into the ladder diagram program generated and edited at a time, search for and extract a partial circuit corresponding to the ladder circuit with the received command name; a display, configured to display input candidates corresponding to the partial circuit extracted by the partial circuit search unit; and a replacement processing unit, configured to, when a selection of the input candidates displayed on the display is received, replace, with the selected input candidate, the ladder circuit of which the command name has been input by the input unit; and a variable setting unit, configured to set a variable of the partial circuit extracted by the partial circuit search unit; the ladder diagram program generation assistance device being characterized in that a search range in which the partial circuit search unit searches for the partial circuit is a range from a first row of the ladder diagram program generated and edited at the time to a row in which the function blocks with presently input command name are added, and wherein the ladder circuit is a circuit that has a logical meaning, and the partial circuit is a single ladder circuit that has a logical meaning or include a plurality of ladder circuits that have a logical meaning, and in that the partial circuit search unit is further configured to search for a ladder circuit that has a command name which is the same as the command name input in the input unit and repeatedly appears a predetermined number of times or more in the search range of the ladder diagram program which is being generated or edited, and extracts a partial circuit in accordance with the searched ladder circuit, and the display is configured to display the partial circuit in which the variables are set by the variable setting unit as the input candidates. an input unit, configured to receive an input related to generation and editing of a ladder diagram program; a partial circuit search unit configured to, when the input unit receives a command name of function blocks related to a ladder circuit to be inserted into the ladder diagram program generated and edited at a time, search for and extract a partial circuit corresponding to the ladder circuit with the received command name; a display, configured to display input candidates corresponding to the partial circuit extracted by the partial circuit search unit; and a replacement processing unit, configured to, when a selection of the input candidates displayed on the display is received, replace, with the selected input candidate, the ladder circuit of which the command name has been input by the input unit; and a variable setting unit, configured to set a variable of the partial circuit extracted by the partial circuit search unit; the ladder diagram program generation assistance device being characterized in that a search range in which the partial circuit search unit searches for the partial circuit is a range from a first row of the ladder diagram program generated and edited at the time to a row in which the function blocks with presently input command name are added, and wherein the ladder circuit is a circuit that has a logical meaning, and the partial circuit is a single ladder circuit that has a logical meaning or include a plurality of ladder circuits that have a logical meaning, and in that the partial circuit search unit is further configured to search for a ladder circuit that has a command name which is the same as the command name input in the input unit and repeatedly appears a predetermined number of times or more in the search range of the ladder diagram program which is being generated or edited, and extracts a partial circuit in accordance with the searched ladder circuit, and the display is configured to display the partial circuit in which the variables are set by the variable setting unit as the input candidates.