PURPOSE:To ensure simple construction with small size and groove type without disturbing magnetic field, by locating the carriage slide shaft and nonmagnetic substance scale plate to the magnetic plate of permanent magnet in a parallel arrangement. CONSTITUTION:The movement of the carriage CA having the solid state generating source LA is made by the linear motor. In the linear motor, permanent magnet PM, magnetip plate Y1, and magnetic slide shaft Y2 form a closed magnetic circuit, and a current flows to the coil wound on the coil bobbin CB which can slide the slide shaft Y2, to move the carriage CA incorporated with the coil bobbin CB with the Fleming's left hand law. The reciprocating movement of the slide shaft Y2 of the carriage CA is made by changing the direction of current flowing to the coil. The signal generating plate, e.g., the slit plate OS of nonmagnetic substance is fixed to the folded terminal Y1H of the magnetic substance plate Y1 for the both ends together with the slide shaft Y2 and it is located in parallel with the slide shaft Y2.