A cooling device of a linear motor to cool a primary side of the linear motor including an iron core and a coil accommodated in slots of the iron core, including an elongate cover covering coil end portions exposed from both side faces of the iron core in a longitudinal direction, an air channel serving as blower for forcing a current of cooling air inside the cover, and a partition plate dividing the inside of the cover into upper and lower spaces. It is configured in such a manner that the upper space divided by the partition plate is used as a ventilation portion through which a current of cooling air is forced and the lower space is used as a cooling portion in which the coil end portions are accommodated and cooled. A slit is formed almost along a full length of the partition plate on a side closer to the iron core for bringing the ventilation portion and the cooling portion into communication with each other, and a vent is provided in a lower portion of the cooling portion.