Measurement device of a property of ink, inkjet printer icluding thereof, and method for sensing ink-condition

A method and apparatus are provided for measuring a physical property of ink, the apparatus having a function of determining whether the ink is in an appropriate state for printing by monitoring a change of a physical property of the ink. The apparatus includes an ink storage unit, a printhead module, a physical property measuring unit, a storage unit, and a determination unit. The ink storage unit stores ink and the printhead module is connected to the ink storage unit to eject the ink onto a printing medium. The physical property measuring unit measures an actual value of the physical property of the ink (for example, electrical conductivity), and the storage unit stores a nominal value of the physical property of the ink, wherein the nominal value is determined in advance at a predetermined temperature. The determination unit compares the actual value with the nominal valued of the physical property of the ink and calculates an error therebetween to determine whether the error is within a predetermined error range.