We analyze static properties of a strongly confined semiflexible polymer, i.e., either trapped in a closed space or compressed by external forces, in an athermal solvent. Like a flexible polymer case, we can resort to an analogy with the semidilute solution, but a complication due to the additional length scale arising from the chain rigidity results in more diverse behaviors depending on system parameters. For each regime, scaling forms of the excess free energy of the confinement are derived. Effects of the confinement geometry and the solvent quality are briefly discussed.