Ceramic waste aggregates (CWAs) were made from electric porcelain insulator wastes supplied from an electric power company, which were crushed and ground to fine aggregate sizes. The CWA mortar as an eco-efficient has been investigated containing ground granulated blast-furnace slag (GGBS). The water-to-binder ratio (W/B) of the CWA mortars was varied at 0.4, 0.5, and 0.6. The GGBS, which enhances the chloride ingress resistance, was utilized as a supplementary cementitious material. The CWA mortars partially replaced by the GGBS at 20% and 40% were immersed into a 5% NaCl solution for 48 and 96 weeks. The chloride diffusion and the pore size distribution were assessed by using an electron probe microanalysis (EPMA) and a mercury intrusion porosimetry at each immersion time. The resistance to the chloride ingress of the CWA mortar was effective in proportion to the GGBS replacement level. The changing of the apparent chloride diffusion coefficients except for the CWA without the GGBS at the W/B of 0.6 was small along the immersion time. Moreover, the apparent chloride diffusion coefficient was well related to the cumulative pore volume less than 0.1 µm of pore diameter.