<；P>；PROBLEM TO BE SOLVED: To provide a laser device in which a residual battery capacitance can be determined. <；P>；SOLUTION: A laser device comprising a secondary battery 2 as a power source for a laser source 8, and the laser device includes a voltage detection unit 3 for detecting a voltage value of the secondary battery 2, a storage unit 5 for storing a remaining battery capacitance prediction table determined in advance, and an arithmetic unit 5. The residual battery capacitance prediction table specifies a predictive residual battery capacitance from the voltage value and a voltage drop per unit time. The arithmetic unit 5 calculates the voltage drop of a voltage per unit time based on the voltage value detected by the voltage detection unit 3, and determines the residual battery capacitance by substituting the calculated voltage drop of the voltage and the voltage value detected by the voltage detection unit 3 to the residual battery capacitance prediction table. <；P>；COPYRIGHT: (C)2007,JPO&INPIT
