A prefilled syringe is provided that has high HEAT resistance, low adsorbability and low moisture permeability and low oxygen permeability. A prefilled syringe containing, as a resin constituting at least a barrel and a joint and a polyester resin that contains a diol unit having a cyclic acetal skeleton in an amount of from 1 to 30% by mol based ON diol units and a dicarboxylic acid unit having a naphthalene skeleton in an amount of 70% by mol or more based ON dicarboxylic acid units, and satisfies the following (i) to (iii): (i) a glass transition temperature of 110C or more measured with a differential scanning calorimeter and (ii) a moisture permeation coefficient of 1 gmm/m 2 /day or less, and (iii) an oxygen permeation coefficient of 10 ccmm/m 2 /day/atm or less.
