Offline teaching device and offline teaching method

An offline teaching device comprising:

• a processor configured to operate as a first determination unit and a second determination unit;
• the first determination unit configured to determine whether data related to production of a workpiece to be produced by welding is changed;
• the second determination unit configured to determine, in a case where the first determination unit determines that the data is changed, a target whose relative position between the workpiece and a welding robot that executes the welding is changed based on the changed data;
• and
• a teaching program creation unit configured to create and output a second teaching program obtained by correcting a first teaching program for executing the welding, based on a displacement amount between a position of the target after the change of the relative position and a position of the target before the change of the relative position.