An organic electroluminescence device (OLED) comprising: a first electrode; a second electrode disposed on the first electrode; and a first light emitting unit disposed between the first electrode and the second electrode, wherein the first light emitting unit includes: a first hole transport region disposed on the first electrode; a first light emitting layer disposed on the first hole transport region and including a host and a dopant; and a first electron transport region disposed on the first light emitting layer and including a hole blocking layer and an electron transport layer disposed on the hole blocking layer, characterized in that the hole blocking layer, and at least one layer of the first light emitting layer and the electron transport layer include a polycyclic compound represented by Formula 1 below: in Formula 1, each of Y 1 to Y 5 and Y 11 to Y 15 is independently CH or N, at least four of Y 1 to Y 5 are CH, at least four of Y 11 to Y 15 are CH, each of R 1 R 2 and R 3 is independently a substituted or unsubstituted alkyl group having 2 to 20 carbon atoms, a substituted silyl group, a substituted boron group, or a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, or forms a substituted or unsubstituted hydrocarbon ring by being coupled to an adjacent group, each of p and q is independently an integer of 1 to 5, and r is an integer of 0 to 8. a first electrode; a second electrode disposed on the first electrode; and a first light emitting unit disposed between the first electrode and the second electrode, wherein the first light emitting unit includes: a first hole transport region disposed on the first electrode; a first light emitting layer disposed on the first hole transport region and including a host and a dopant; and a first electron transport region disposed on the first light emitting layer and including a hole blocking layer and an electron transport layer disposed on the hole blocking layer, a first hole transport region disposed on the first electrode; a first light emitting layer disposed on the first hole transport region and including a host and a dopant; and a first electron transport region disposed on the first light emitting layer and including a hole blocking layer and an electron transport layer disposed on the hole blocking layer, characterized in that the hole blocking layer, and at least one layer of the first light emitting layer and the electron transport layer include a polycyclic compound represented by Formula 1 below: in Formula 1, each of Y 1 to Y 5 and Y 11 to Y 15 is independently CH or N, at least four of Y 1 to Y 5 are CH, at least four of Y 11 to Y 15 are CH, each of R 1 R 2 and R 3 is independently a substituted or unsubstituted alkyl group having 2 to 20 carbon atoms, a substituted silyl group, a substituted boron group, or a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, or forms a substituted or unsubstituted hydrocarbon ring by being coupled to an adjacent group, each of p and q is independently an integer of 1 to 5, and r is an integer of 0 to 8. each of Y 1 to Y 5 and Y 11 to Y 15 is independently CH or N, at least four of Y 1 to Y 5 are CH, at least four of Y 11 to Y 15 are CH, each of R 1 R 2 and R 3 is independently a substituted or unsubstituted alkyl group having 2 to 20 carbon atoms, a substituted silyl group, a substituted boron group, or a substituted or unsubstituted aryl group having 6 to 30 ring-forming carbon atoms, or forms a substituted or unsubstituted hydrocarbon ring by being coupled to an adjacent group, each of p and q is independently an integer of 1 to 5, and r is an integer of 0 to 8.