To provide a T-shirt printing system with which a pattern, etc., are beautifully printed on a T-shirt by using an ink-jet printer.

The clothing printing method comprises, in a T-shirt printing system 1, inserting a T-shirt elongation tool 4 in a closed state into a T-shirt 5 of a printing target, opening the T-shirt elongation tool 4, pushing and extending the body part 51 of the T-shirt 5 right and left so as to draw out the front part 51a and the back part 51b of the body part into a plane state (clothing drawing out process), then placing the T-shirt 5 in a state in which the T-shirt is pushed and extended right and left by the T-shirt elongation tool 4 on a medium placing base 22 of an ink-jet printer 2 so as to lay the front part 51a upward (clothing setting process), driving the ink-jet printer 2 and printing a printing image on a set position in the front part 51a of the body part 51 of the T-shirt.