  We report spatially resolved tunneling spectroscopic evidence for
field-induced microscopic orders in a high-$T_c$ superconductor $\rm
YBa_2Cu_3O_{7-\delta}$. The spectral characteristics inside vortices reveal a
pseudogap ($V_{\rm CO}$) larger than the superconducting gap ($\Delta\_{\rm
SC}$) as well as a subgap ($\Delta\^{\prime}$) smaller than $\Delta\_{\rm SC}$,
and the spectral weight shifts steadily from $\Delta_{\rm SC}$ to $V_{\rm CO}$
and $\Delta\^{\prime}$ upon increasing magnetic field. Additionally,
energy-independent conductance modulations at 3.6 and 7.1 lattice constants
along the Cu-O bonding directions and at 9.5 lattice constants along the nodal
directions are manifested in the vortex state. These wave-vectors differ
fundamentally from the strongly dispersive modes due to Bogoliubov
quasiparticle scattering interferences and may be associated with field-induced
microscopic orders of pair-, charge- and spin-density waves.
