Men's singles
1998 Japan Open Tennis Championships
Final
Champion	Andrei Pavel[1]
Runner-up	Byron Black
Score	6–3, 6–4
Details
Draw	56
Seeds	16
Events
Singles men women Doubles men women
← 1997 · Japan Open · 1999 →

The 1998 Japan Open Tennis Championships was a tennis tournament played on outdoor hard courts at the Ariake Coliseum in Tokyo in Japan that was part of the International Series Gold of the 1998 ATP Tour and of Tier III of the 1998 WTA Tour. The tournament was held from April 13 through April 19, 1998.

Champion seeds are indicated in bold text while text in italics indicates the round in which those seeds were eliminated.

	Semifinals							Final[1]
		Andrei Pavel	6	6
	11	Jan-Michael Gambill	4	3
								16	Andrei Pavel	6	6
								10	Byron Black	3	4
	10	Byron Black	6	7
	12	Daniel Vacek	3	5

	First round							Second round							Third round							Quarterfinals
								1	P Rafter	3	6
		B MacPhie	7	6					B MacPhie	6	7
		K Flygt	6	4												B MacPhie	6	3	4
		R Vašek	6	4	7										16	A Pavel	3	6	6
		S Lareau	4	6	6				R Vašek	7	0	5
	16	A Pavel	6	6				16	A Pavel	5	6	7
		O Delaître	3	0																		16	A Pavel	6	7
	9	S Campbell	6	7																			D DiLucia	3	6
		A Richardson	1	6				9	S Campbell	3	6
		I Heuberger	6	6					I Heuberger	6	7
		S Matsuoka	3	3												I Heuberger	3	6	3
		D DiLucia	6	3	6											D DiLucia	6	0	6
		David Wheaton	3	6	3				D DiLucia	4	6	6
								8	K Carlsen	6	3	3

	First round							Second round							Third round							Quarterfinals
								3	T Henman	6	7
		D Nestor	6	6					D Nestor	2	5
		N Godwin	2	2											3	T Henman	6	6
		S Iwabuchi	7	0											14	J Golmard	4	1
		D Sapsford	5	1r					S Iwabuchi	4	4
	14	J Golmard	6	3	6			14	J Golmard	6	6
		T Chaen	2	6	1																	3	T Henman	3	6	3
	11	J-M Gambill	6	6																		11	J-M Gambill	6	4	6
		S Pescosolido	3	2				11	J-M Gambill	6	6
		K Miyachi	6	6					K Miyachi	0	;3
		A Belobrajdic	2	1											11	J-M Gambill	6	6
		R Schüttler	6	3	6											R Schüttler	0	0
		C Vinck	4	6	3				R Schüttler	6	6
								6	M Damm	2	4

	First round							Second round							Third round							Quarterfinals
								5	V Spadea	3	0
		S Stolle	6	6					S Stolle	6	6
		T Suzuki	2	3												S Stolle	5	3
		G Motomura	4	6	7										12	D Vacek	7	6
		C Wilkinson	6	4	5				G Motomura	2	2
	12	D Vacek	6	6				12	D Vacek	6	6
		V Santopadre	1	1																		12	D Vacek	6	6
	13	M Tillström	4	6	6																		D Prinosil	4	1
		K Masuda	6	3	0			13	M Tillström	5	6	6
		A O'Brien	6	6					A O'Brien	7	4	4
		Ó Burrieza	2	0											13	M Tillström	4	6
		D Prinosil	6	6												D Prinosil	6	7
		M Sell	2	1					D Prinosil	6	6
								4	T Johansson	3	3

	First round							Second round							Third round							Quarterfinals
								7	G Pozzi	3	6
		C Caratti	6	7					C Caratti	6	7
		B Ellwood	0	6												C Caratti	3	4
		L Burgsmüller	6	6											10	B Black	6	6
		S Koubek	4	1					L Burgsmüller	4	2
	10	B Black	3	7	6			10	B Black	6	6
		J Stark	6	6	4																	10	B Black	6	6
		H Dreekmann	6	6																			H Dreekmann	2	3
	15	A Clément	3	4					H Dreekmann	7	7
		T Ketola	6	6					T Ketola	6	6
		M Tebbutt	4	4												H Dreekmann	6	5	6
		J van Lottum	6	0	7										2	M Chang	2	7	4
		H Kaneko	4	6	5				J van Lottum	4	1
								2	M Chang	6	6