PROBLEM TO BE SOLVED: To provide a schedule management device in a manufacturing plant capable of suppressing deviation between a schedule and an operation due to operation change.SOLUTION: A schedule management device in a manufacturing plant includes: a schedule data storage unit for storing scheduled start time and scheduled finish time of all the steps; an actual result data storage unit for collecting actual result data of the start time and the finish time of all the steps and storing it, according to the progress of an operation; a schedule actual result comparison unit for calculating a time error between the actual result and the schedule from the actual result data stored in the actual result data storage unit and the data stored in the storage unit; an error factor input unit for inputting a factor of the time error; an error statistic value calculation unit for calculating a statistic value regarding the time error for each factor; an error factor storage unit for storing the factor inputted in th
