An occupant classifying device for a vehicle includes a load detection device for detecting a load applied on a vehicle seat, a control device for judging classification of an occupant on the basis of load data inputted from the load detection device, and a communication control portion provided on the control device, the communication control portion for controlling bilateral communication conducted between the load detection device and the control device. The bilateral communication is conducted at different communication speeds on the basis of a communication state of the bilateral communication or an operational state of the control device.