To prevent data which cannot be reproduced in respective terminal units from being transmitted even if a user does not input a format and a parameter at every time in a contents conversion transmission device converting the format of digital data and transmitting it to the plural types of terminal units.

The device is provided with a contents input means 11 inputting digital data, a contents output means 19 transmitting digital data to the terminal unit, a terminal selecting means 14 selecting the type of the terminal unit of a transmission opposite party, a format input means 15 to which the type of data which can be reproduced in the terminal unit and the parameter on the format are inputted for each type of the terminal unit, a format storage means 16 storing the inputted parameter and a contents conversion means 17 reading the parameter from the format storage means and converting the format of digital data.