  We have investigated the magnetic and dielectric properties of
Ca$_2$CoSi$_2$O$_7$ crystal. The dielectricity and magnetism of
Ca$_2$CoSi$_2$O$_7$ are strongly coupled below a canted antiferromagnetic
transition temperature ($T_{\rm N}$): Magnetic fields induce electric
polarization below $T_{\rm N}$. Interestingly, the magnetic-field-induced
electric polarization is detected even without poling electric fields. Below
$T_{\rm N}$, a canted antiferromagnetic-paramagnetic transition is induced by
magnetic fields. The large magnetocapacitance is observed around $T_{\rm N}$.
The origin of the large magnetocapacitance is due to the magnetic-field-induced
the canted antiferromagnetic-paramagnetic transition.
