Conditional stability of explicit schemes in finite differences complicates the choice of a time step. The increase in the number of the grid nodes for more precise computations and the corresponding space step decrease leads to the increase in computer costs due to the decreasing of the time step. We present a new implicit scheme for computing Maxwell's equations in three-dimensional domains, where the smallest size is one tenth or less than any other size. The main advantage of the new scheme is possibility of performing the computations with bigger time steps, the disadvantage is a possible high level of errors for short-wave solutions. The first numerical results of the scheme behavior are presented.