A phosphor substituting the conventional sialon phosphor or oxide phosphor activated by rare earth and an application thereof are provided. The phosphor of the present invention comprises an inorganic crystal including at least La, Si, Al, N (nitrogen), M element (M is at least one kind of element selected from the group consisting of Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb), and O (oxygen) if necessary and the inorganic crystal is a host crystal, which is LaSi9Al19N32 crystal or a solid-solution crystal thereof, activated by the M element.