PURPOSE: To obtain a stable freeze-dried preparation exhibiting remarkable stabilizing effect, by adding sodium chloride to a specific carbapenem derivative.

CONSTITUTION: A carbapenem derivative of formula such as (5R,6S,8R)-2-[(3S)-1- acetimidoylpyrrolidin-3-ylthio ]-6-( 1-hydroxyethyl )-2-carbapenem-3-carboxylic acid, etc. exhibiting broad antibacterial spectrum against Gram-positive and negative bacteria or its salt e.g. an alkali metal salt such as Na, K salt, etc., is dissolved together with sodium chloride in water such as distilled water for injection. A definite amount of the solution is filled in a vial, ampule, etc., freeze-dried, and sealed by capping or welding to obtain the objective stable freeze-dried preparation.