To provide a safe and efficient core sampling method of the sea bottom ground for reducing a piloting burden and cost.

This core sampling method comprises a process of seating and arranging a sea bottom core sampling device on the sea bottom by suspending the device, a process of separating the sea bottom core sampling device from a rope of a work ship by releasing the connection with the rope by releasing a connecting mechanism, a process of gathering a sample by excavating the sea bottom ground by the sea bottom core sampling device, a process of stopping the work ship on the sea of the point by specifying a position of an ultrasonic transceiver after finishing the sample gathering process, and a process of suspending and recovering the sea bottom core sampling device by suspending an intermediate part of the rope attached with the ultrasonic transceiver by a rope holding mechanism installed on the tip of the rope delivered from the work shape while confirming the position of the ultrasonic transceiver by transmitting an ultrasonic wave from the work ship.