A travelling track on which a plurality of movers travel is divided into sections of various lengths. The treating instrument erecting member is provided at the distal end of an insert part of the endoscope. A mechanism moves the water trap between a first position in which the nonlinear component of the intermediate section is above the axis and a second position in which the nonlinear component of the intermediate section is substantially at the axis. In wells where one or more antimicrobial agents are present only pathogens resistant to the antimicrobial agent grow.