A corrosion-resistant silicon nitride ceramics in which an adhesion enhancing layer (3), a stress relaxing layer (4) and a crack extension preventing layer (5) are laminated in this order on a ceramic substrate (2) composed mainly of silicon nitride, and a surface corrosion-resistant layer (6) composed mainly of zirconium oxide stabilized by an element of the group 3a of the periodic table is laminated. The thermal expansion coefficient (.alpha..sub.0) of the ceramic substrate (2), the thermal expansion coefficient(.alpha..sub.1) of the adhesion enhancing layer (3), and the thermal expansion coefficient (.alpha..sub.2) of the stress relaxing layer (4), the thermal expansion coefficient (.alpha..sub.3) of the crack extension preventing layer (5), and the thermal expansion coefficient (.alpha..sub.4) of the surface corrosion-resistant layer (6) satisfy the following relational expressions (I) to (III): .alpha..sub.0.apprxeq..alpha..sub.1 (I) .alpha..sub.3<.alpha..sub.2 (II) .alpha..sub.3<.alpha..sub.4 (III).