To provide a drive-through car washing machine capable of preventing a washing machine body from excessively approaching a vehicle due to wrong detection of a vehicle to move out after washing, and from taking a long time to return to a stand-by position.

A photo detector 14b of a transmission type photoelectric sensor 14 comprising a projector 14a and the photo detector 14b, and a reflection type photoelectric sensor 15 are provided on a rear face of the car washing machine body 1 capable of running. A detection area 15a of the reflection type photoelectric sensor 15 includes more inward side than an optical axis 14c of the transmission type photoelectric sensor 14. After washing for the vehicle V is finished, when the car vehicle V moving out is detected by the photoelectric sensor 14, 15 while the washing machine body 1 is reciprocating, running of the car washing machine body 1 is stopped.