A connector assembly includes a first connector having a tubular first connector body, a hollow needle inside the first connector body and a first sealing component piercable by the needle, and a second connector having a tubular second connector body and a second sealing component. The second sealing component is in the second connector body, is attached to a first piercing section when inserted into the first connector body, and, in that state, is pierced by the needle together with the first piercing section. The connector assembly also includes a restriction which, when the second connector is inserted into the first connector, temporarily interrupts and restricts the insertion operation, but allows resumption of such operation when the restriction is removed, and which, when the second connector is withdrawn from the first connector, temporarily interrupts and restricts the withdrawing operation, but allows such operation to resume when the restriction is removed.