  Study of boundary phase transition in toric code under cylinder geometry via
bulk projective measurement is reported. As the frequency of local measurement
for bulk qubits is increased, spin-glass type long-range order on the
boundaries emerges indicating spontaneous-symmetry breaking (SSB) of $Z_2$
symmetry. From the lattice-gauge-theory viewpoint, this SSB is a signal of a
transition to Higgs phase with symmetry protected topological order. We
numerically elucidate the properties of this phase transition in detail,
especially its criticality, and give a physical picture using non-local
gauge-invariant symmetry operators. Phase transition in the bulk is also
studied and its relationship to the boundary transition is discussed.
