To provide an opening and closing type window grille for keeping beauty of external appearance of a window part without protruding the window grille to the outdoor side of a window by installing the window grille in the indoor side of a window sash, and provided with a lock device that can be easily operated.

The opening and closing type window grille 20 installed in the indoor side of the window sash comprises: a lock member 61 having a first protrusion part 65B pushed by a grille member by movement of the grille member 32 of an edge during closing the window grille to rotate the lock member by rotatably providing the lock device R preventing movement to a storing part side of a grille member on a guide rail 21 during closing the window grille, and a second protrusion part 65A positioned at the storing part side of the grille member accompanying rotation of the lock member to prevent movement to the storing part side of the grille member; and a stopper 67 engaged with the lock member and preventing rotation of the lock member during movement prevention of the grille member of the lock member.