The present specification discloses a programmable controller which comprises bit operation memory for storing a mixed instruction inclusive of the mixture of bit operation instructions and word operation instructions in order of execution; a word operation memory for storing the word operation instructions in said mixed instruction in order of execution; a bit operation processor for outputting a start command for a word operation instruction when recognizing that word operation instruction read from said bit operation memory subsequently to the execution of the bit operation instruction; and a microprocessor for receiving said word operation start command to execute said word operation instruction stored in said word operation memory.