Controller

A controller that reteaches taught positions in blocks contained in a plurality of machine control programs for controlling a plurality of mechanisms, each of the plurality of machine control programs including at least one piece of linkage information that indicates linkage between blocks of the machine control programs, the controller comprising:

• a teaching information management table in which the linkage information and taught positions in blocks of the plurality of machine control programs that are indicated by the linkage information as being linked to one another are associated with each other and managed;
• a machine position acquiring section that acquires current positions of the mechanisms;
• a reteach block search section that assigns with reference to the teaching information management table rank order numbers to the linkage information on the basis of relation between the current positions of each of the mechanisms acquired by the machine position acquiring section and a taught position in a block of the plurality of machine control programs that relates to the linkage information;
• a search result output section that outputs blocks of the plurality of machine control programs that relate to the linkage information on the basis of the rank order numbers assigned by the reteach block search section;
• and
• a reteach result reflecting section that reflects, in blocks of the plurality of machine control programs that have been selected as blocks to be retaught among the blocks output by the search result output section, the current positions of the mechanism that have been obtained by the machine position acquiring section as positions to be retaught.