A catheter assembly includes: a catheter； a catheter hub； an inner needle； a needle hub； and a deflection suppressing mechanism suppressing deflection of the inner needle. The deflection suppressing mechanism includes an upper deflection suppressing portion positioned on an upper side of the inner needle and a lower deflection suppressing portion positioned on a lower side of the inner needle. At least one of the upper deflection suppressing portion and the lower deflection suppressing portion is movable with respect to the needle hub.
