  We examine the first order Fermi acceleration on the presumption that
supernova remnant shocks cross ambient magnetic fields with various angles.
These oblique shocks accelerate particles more efficiently than the parallel
shocks and elevate the maximum energies achievable by the particles. The
primary cosmic ray spectrum is strongly dependent upon these energies. We also
consider the dependence of the injection efficiency and of spectral indices on
obliquity. When indices and absolute fluxes at $10^{12}$ eV are given for six
nuclear groups from balloon-borne data, each energy spectrum develops a smooth
rigidity dependent knee structure. The resultant total spectrum also behaves
similarly and fits well with ground-based experimental data up to several
$10^{17}$ eV. It is shown as well that the chemical composition changes
significantly from lighter to heavier nuclei as the energies of particles
exceed the knee region. Other predicted curves are compared with the
experimental data which they reproduce rather well.
