The objective of this research is to devise methods to modify the CRS for low birth weight infants from the perspective of the posture of low birth weight infants when the CRS is used. The study was carried out using the infants who weigh 1.850 grams to 3.600 grams at the time when the CRS was used and whose corretive age were thirty-four to forty-two weeks. We checked and analyzed the oxygen saturation, the body temperature. and the posture of the infant in the CRS. The results of the study revealed the following: 1. As the CRS which conforms to the standards of the Japanese model standand by the Ministry of Transport is not suitable for the physique of the low birth weight infants, it is necessary to use towels and such to fill the void in the CRS. 2. When towels and such are used to fill the void in the CRS. it was found that the movement of the infants and the vibratory motion generated during transport create the void which had initially been filled. Furthermore. the deterioration in oxygen saturation was observed in such instances as when the body of the infant hunched, when the jaw lowered. when the neck bent slightly. or when some vibration was caused by railroad crossings or road bumps. 3. As for the CRS the void of which was filled with the sewn cushion material such as urethane foam, it caused the body to hunch. which then caused a worsening of the posture with the lowered jaw and the slightly bent neck. However. the level of deterioration in oxygen saturation was not significant. 4. About the change in the skin temperature measured at the back of the neck. about 0.1 degree rise in the body temperature was observed statistically. 5. We were able to gain from the study the indicators that would help us modify the CRS. which conform to the standards. for the low birth weight infants to ensure safer transport.