Abstract: A method for charging a catalyst in particles to a tubular reactor having many vertically arranged reactor tubes of a definite length, which comprises inserting a wire formed in an optional shape into each reactor tube at the upper opening thereof, supplying the catalyst particles to the reactor tube to allow them to fall along the wire and gradually withdrawing the wire with or without vertical fluctuation as the height of the filled catalyst layer increases, thereby slowing down the falling velocity of the catalyst particles to prevent them from being crushed or powdered and at the same time obtaining a uniform bulk density of the filled catalyst.