PURPOSE: To provide a sentence preparation device which reduces the burden of an operator by means of automatically calculating and displaying to which day, month and year the date is applied in respective calendars only by designating a prescribed date, day expression, for or example.

CONSTITUTION: When 'senshu no suiyobi' (last Wednesday) is inputted from an input part 1, a KANA(Japanese syllabary)-KANJI(Chinese character) conversion part 2 converts it. When a day expression/date conversion key is depressed, a day expression/date conversion processing part 5 displays the date applied to 'last Wednesday', '27th of March 1991' expressed in the Christian Era, for example, in a display part 3 as a candidate date. When a next candidate key is depressed, the date candidate character string of '27th of March, Heisei 3' expressed in a Japanese Era is displayed. When a decision key is depressed in the display state of the Christian Era or the Japanese Era, the date by the calendar is decided.