Paddy rice (Oryza sativa L.) is a staple crop in most East and Southeast Asian countries. However, across Asia, cadmium (Cd) has increasingly accumulated in paddy soil owing to the use of phosphate fertilizers and the release of industrial effluents into irrigation channels that are used for flooding paddy fields. The food safety risk posed by increasing Cd levels in rice is of great concern. Information about the genotypic variations of Cd tolerance, distribution, and accumulation in rice plants is essential for selecting and breeding more rice cultivars to reduce Cd in human diets. At present, variations in the Cd levels in rice plants and accumulation in rice grains are still not considered during rice breeding in Taiwan. A physiological understanding of genotypic variations in Cd contents in rice grains would be useful for better selecting or breeding low Cd-accumulation rice genotypes. The present study aims to investigate Cd absorption and toxicity in different rice cultivars and to clarify their relationship with the physiological response to Cd stress. This study conducted a hydroponic experiment to investigate rice genotypic variations in Cd absorption and toxicity related to plant physiological traits. Eight paddy rice cultivars were selected based on the criteria of rice grains quality in Taiwan. These rice cultivars were of three different types: japonica (TY3, TK9, TNG71, and KH145 cultivars), indica (TCS10 and TCS17 cultivars), and glutinous (TKW1 and TKW3 cultivars). Uniformly grown seedlings were drawn up for Cd treatment with 50 µM CdCl₂ in hydroponics for 7 days; a check was set at 0 µM CdCl₂. In results, the reductions of shoot growth were more significant than those of root growth for the rice cultivars with Cd treatment. However, absorbed Cd was preferentially accumulated in the root than in the shoot. This suggested that less Cd transfer from the root to the shoot would be related to higher Cd tolerance and shoot growth improvement. The oxidative statuses of rice plant under Cd stress depended on the configurations of H₂O₂ in the root and shoot and the oxidative damages of Cd stress were determined by the malondialdehyde (MDA) contents in plant. The results showed more enhanced MDA by Cd treatment in the root than in the shoot. This consisted with that the superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities were more pronounced in the shoot than in the root. The regulation tendencies of SOD and APX were also related to the Cd preferential accumulation in the root. Therefore, the root would play a role in protecting the shoot from oxidative damages of Cd stress for rice plants.