To obtain a card type metric system unit conversion scaler which need not have a scale, etc., moved for unit conversion and enables even a child to easily and instantaneously perform unit conversion and is convenient to carry by viewing a number through a cut part or transparent part and performing unit conversion.

One thin plate 1 is provided with lines 7 to 11 which display quantities, line by line (line 2 to 6), for respective quantities and their units and are used to read the movement of a decimal point resulting from unit conversion. Here, when two kinds of unit, e.g. m3 and l are displayed for volume, they may be displayed on the different lines 4 and 5. The lines 7 to 11 for reading the movement of the decimal point as a result of unit conversion, on the other hand, are cut so as to write numbers to a book, etc., and also provided below the lines 2 to 6 where the quantities and units are displayed. Further, those lines 7 to 11 may be made transparent that the movement of the decimal point resulting from the unit conversion can be seen through and read.