The diagram creation device ensures a good response irrespective of the volume of data while realizing a wide variety of display modes of figures or tables based on data acquired from a database. The function treating section of the diagram creation device returns a data produced by a content of an instruction input into a cell of a worksheet of a spreadsheet soft. The data treating section acquires data specified by a function and an entire time-series data having a code which forms argument of the function from a local database and then stores into a data caching section. The data acquired from the local database are computed to produce a computed data and stored into a computed data caching section. When data specified by the function exists within the data caching section or a computed data caching section, the data treating section preferentially acquires them.