To provide a counter capable of acquiring an accurate value of the number of pulse trains externally received in a short time and to provide a counter system.

The counter 1 for receiving pulse trains from the outside of the counter to count the number of pulse trains wherein a controller 2 for using the count for its control reads the count, is configured to include: a means 8 for latching the count indicating the number of pulse trains when the counter 1 receives a trigger signal from the outside of the counter 1 during the count processing of the pulse trains; a means 11 for issuing interrupt to the controller 2 when receiving the trigger signal; and a means 12 for clearing the latched pulse count when reading of the latched pulse count is completed.