A rolling bearing sealing device comprising a seal fixable to an outer ring and a slinger disposed concentrically with an inner ring on a side of the seal which faces an outside of the bearing or an axially outer side of the seal, a space defined by the seal and the slinger being open to an exterior portion of the bearing, the rolling bearing sealing device comprises: an axial lip which expands radially outwards of the bearing is formed on a side surface of the seal which faces the slinger, a surface of the slinger which faces the seal is made into a flat surface and a projecting portion is formed on the flat surface of the slinger which is caused to project inwards of the bearing relative to the flat surface by flexing the slinger in an axial direction, a distal end of the axial lip is put in a contacting state with or a non-contact, closely lying state to the flat surface of the slinger at a portion lying further radially outwards than the projecting portion on the slinger, and a radially inwards inner surface of the axial lip and a radially outer side sloping surface which is formed radially outwards of the projecting portion on the slinger are put in a non-contact, closely lying state to each other so as to form a labyrinth, characterized by a portion of the side surface of the seal which lies further radially inwards than the position where the axial lip is formed and an apex portion of the projecting portion on the slinger are put in a non-contact, closely lying state to each other so as to form a labyrinth, and a projecting portion projecting outwards of the bearing is formed on the side surface of the seal at a portion which lies further radially outwards than the distal end of the axial lip and the projecting portion and the slinger are put in a non-contact, closely lying state to each other so as to form a labyrinth. an axial lip which expands radially outwards of the bearing is formed on a side surface of the seal which faces the slinger, a surface of the slinger which faces the seal is made into a flat surface and a projecting portion is formed on the flat surface of the slinger which is caused to project inwards of the bearing relative to the flat surface by flexing the slinger in an axial direction, a distal end of the axial lip is put in a contacting state with or a non-contact, closely lying state to the flat surface of the slinger at a portion lying further radially outwards than the projecting portion on the slinger, and a radially inwards inner surface of the axial lip and a radially outer side sloping surface which is formed radially outwards of the projecting portion on the slinger are put in a non-contact, closely lying state to each other so as to form a labyrinth, characterized by a portion of the side surface of the seal which lies further radially inwards than the position where the axial lip is formed and an apex portion of the projecting portion on the slinger are put in a non-contact, closely lying state to each other so as to form a labyrinth, and a projecting portion projecting outwards of the bearing is formed on the side surface of the seal at a portion which lies further radially outwards than the distal end of the axial lip and the projecting portion and the slinger are put in a non-contact, closely lying state to each other so as to form a labyrinth.