The present invention provides a luminescence measuring method that can be accurately and quickly carried out while inhibiting a possible background associated with viable bacteria adhering to a nozzle or Adenosine Tri Phosphate remaining in the nozzle, and an apparatus for the method. The present invention uses a washing apparatus characterized by including a nozzle, a lysys solution, a luminescence reagent solution, and a detection section, as well as a relevant washing method and a relevant luminescence measuring method. To remove viable bacteria adhering to the nozzle, the nozzle is immersed in the lysys solution and then in the luminescence reagent solution. The detection section monitors luminescence occurring during a washing process.