Spontaneous　symmetry　breaking　(SSB)　is　crucial　to　the　occurrence　of　phase　transitions.　Once　a　phase　transition　occurs,　a　quantum　system　presents　degenerate　eigenstates　that　lack　the　symmetry　of　the　Hamiltonian.　After　crossing　the　critical　point,　the　system　is　essentially　evolved　to　a　quantum　superposition　of　these　eigenstates　until　decoherence　sets　in.　Despite　the　fundamental　importance　and　potential　applications　in　quantum　technologies,　such　quantum-mechanical　SSB　phenomena　have　not　been　experimentally　explored　in　many-body　systems.　We　here　present　an　experimental　demonstration　of　the　SSB　process　in　the　LipkinMeshkov-Glick　model,　governed　by　the　competition　between　the　individual　driving　and　intraqubit　interaction.　The　model　is　realized　in　a　circuit　quantum　electrodynamics　system,　where　6　Xmon　qubits　are　coupled　in　an　all-to-all　manner　through　virtual　photon　exchange　mediated　by　a　resonator.　The　observed　nonclassical　correlations　among　these　qubits　in　the　symmetry-breaking　region　go　beyond　the　conventional　description　of　SSB,　shedding　new　light　on　phase　transitions　for　quantum　many-body　systems.