PURPOSE: To enable high grade training by providing a feed device of a trainer to control the feed device on the basis of a load center position of a trainee measured by a measurer.

CONSTITUTION: When a trainee moves on a measurer 7, the outputs of load cells L1-L4 are varied. Load measuring values are figured out by a load converter to be put sequentially in a controller 5 so that the present position, moving direction and moving speed of the trainee are calculated. A tennis ball 2 strikes the rear and upper surfaces of a net 3 so that the position, momentum and direction of the ball are measured to be sent to the controller 5 which generates a command about ball feed to a feed device 4 on the basis of such information. A plurality of tennis balls 2 are supplied to the ball feed device 4 which feeds the tennis ball 2 to the trainee by changing the direction and speed thereof according to the command of the controller 5, and the trainee can return the ball to perform high grade training.