Droplet detection device and ink jet printer

A droplet detection device that detects a droplet discharged from a nozzle of a head of an ink jet printer based on presence or absence of shielding of a detection light by the droplet, the droplet detection device comprising:

• a light emitting element that emits the detection light in a direction intersecting an advancing direction of the droplet discharged from the nozzle;
• a light receiving element that receives the detection light emitted from the light emitting element;
• and
• a pair of wall portions disposed facing each other with a spacing through which the droplet passes;
• wherein
• the pair of wall portions are arranged along a light path so that at least a part of the light path of the detection light from the light emitting element to the light receiving element passes between the pair of wall portions;
• and
• at least a part of the detection light is guided toward the light receiving element side while being reflected at respective opposing surfaces of the pair of wall portions in a region between the pair of wall portions in the light path.