Head of Program editing

Ladder program editing apparatus (60), - a positive busbar (Bp) and a negative busbar (Bm) causes in a ladder diagram, to be displayed on a screen of a display unit (20), - which causes a plurality of auxiliary lines (AL), whereby the area into a plurality of cells (Ce) is partitioned are displayed vertically and laterally in a range between the positive busbar and the negative busbar, - causing that circuit elements (X1-X999, Y10) forming a ladder diagram is displayed symbolically in mutually separated cells, and - which, editing a ladder diagram in which at least one input condition of an output condition corresponding with an input unit (10) which inputs a self-related to the editing of the ladder diagram command; and an editing control (25) - circuit elements (X1-X999, Y10) in arranging cells on the screen of the display unit (20), and - based on a command from the input unit (10) - data of a logical expression (I-XII) according to a logical structure in the ladder diagram generated based on the arrangement of the circuit elements (X1-X999, Y10), by specifying the arranged circuit elements (X1-X5, X6) in each row as a parallel with each other to be connected to circuit unit (CU - based on a command to draw a connecting line from the input unit - circuit elements (X1-X999, Y10), which are to be connected in parallel in the ladder diagram specified based on the data of the logical expression (I-XII), and - connecting output ends of the circuit elements (X1-X999, Y10) by a connecting line.