There is a need to maintain or enhance the magnetic field correction accuracy of a physics package while making the physics package more compact and portable. A triaxial magnetic field correction coil is provided inside a vacuum chamber surrounding a clock transition space having atoms disposed therein. The triaxial magnetic field correction coil is formed into a shape such that it is possible to correct, for magnetic field components of three axial directions passing through the clock transition space, a constant term, a first order spatial derivative term, a second order spatial derivative term, a third or higher order spatial derivative term, or some given combination of these terms. The triaxial magnetic field correction coil can be used in, for example, a physics package for an optical lattice clock.