a lamp unit mounting structure includes a mounting panel having a mounting portion , a lamp unit , an elastic fixing member and a restricting member . the elastic fixing member is provided on the lamp unit , and includes a first portion which is extended from the lamp unit , a second portion which has a substantially u - shape , and has a first end being integrally connected to the first portion , a third portion which is extended from a second end of the second portion toward the lamp unit . the engagement portion engages the mounting portion of the mounting panel . the restricting member is provided on the lamp unit , and restricts a movement of the elastic fixing member in a mounting and dismounting direction of the engagement portion relative to the mounting panel . the restricting member has an escape portion which allows a movement of the elastic fixing member toward the lamp unit .