A bezel member (52) to which a lens (54) which transmits light from a light source (37) is supported on a main body (30) to be fixed to a vehicle body (11). A spherical surface (52a) is formed on one of the main body (30) or a bezel member (52), and sliding members (34) for being pressed against the spherical surface (52a) are formed on the other one of them, so that the bezel member (52) can be rotated with respect to a supporting member (33) of the main body (30) and fixed to a given position. Since a metal plate is used as the sliding members (34) in this interior illumination lamp (10), a problem such that the light source cannot be fixed to the desired direction due to abrasion or change of properties of the felt sliding member as in the related art due to the temperature or deterioration with age can be solved. Also, in comparison with the case in which the spring or the like is employed, increase in cost due to increase in the number of parts can be avoided.