The men's 400 metres at the 2013 European Athletics Junior Championships was held in Rieti on 18 and 19 July.

Prior to the competition, the existing world junior and championship records were as follows.

World Junior Record	Steve Lewis (USA)	43.87	Seoul, South Korea	28 September 1988
European Junior Record	Thomas Schönlebe (GDR)	45.01	East Berlin, East Germany	15 July 1984
Championship Record	Roger Black (GBR)	45.36	Cottbus, East Germany	24 August 1985
World Junior Leading	Arman Hall (USA)	44.82	Des Moines, IA, United States	21 June 2013
European Junior Leading	Patryk Dobek (POL)	46.34	Kraków, Poland	4 July 2013

Qualification: First 3 in each heat (Q) and 4 best performers (q) advance to the semifinals.^[1]

Rank	Heat	Name	Nationality	React	Time	Notes
1	3	Pavel Ivashko	Russia		46.24	Q, PB
2	4	Thomas Jordier	France	0.158	46.71	Q, PB
3	4	Patryk Dobek	Poland	0.181	46.89	Q
4	2	Luka Janezic	Slovenia	0.169	47.06	Q, PB
5	4	Dennis Forsman	Sweden	0.169	47.15	Q, PB
6	2	Bastien Mandrou	France	0.215	47.20	Q
7	3	Oleksiy Pozdnyakov	Ukraine		47.21	Q, PB
8	4	Milos Raovic	Serbia	0.239	47.22	q
9	3	Ben Snaith	Great Britain		47.26	Q
10	2	Rafal Smolen	Poland	0.160	47.29	Q
11	3	Bálint Móricz	Hungary		47.41	q
12	3	Aliaksandr Krasouski	Belarus		47.57	q
13	1	Mateo Ruzic	Croatia	0.173	47.42	Q
14	2	Sondre Nyvold Lid	Norway	0.202	47.71	q, SB
15	2	Batuhan Altintas	Turkey	0.158	47.82
16	1	Danil Peremetov	Russia	0.209	47.85	Q
17	1	Marc Koch	Germany	0.235	47.86	Q
18	3	Kolbeinn Hödur Gunnarsson	Iceland		48.06	PB
19	2	Josip Sakic	Croatia	0.184	48.11	PB
20	2	Francesco Conti	Italy	0.172	48.14
21	4	Mirko Romano	Italy	0.178	48.16	PB
22	1	Doruk Ugurer	Turkey	0.168	48.22
23	1	Dávid Bartha	Hungary	0.180	48.24
24	4	Lukas Privalinec	Slovakia	0.289	48.30
25	3	Adrian Yannis Nicula	Romania		48.41
26	1	Luca Cropelli	Italy	0.169	48.57
27	1	Lucas Bua	Spain	0.160	49.24
	4	Dmitriy Khasanov	Russia		DQ

Qualification: First 3 in each heat (Q) and 2 best performers (q) advance to the final.

Rank	Heat	Name	Nationality	React	Time	Notes
	1	Aliaksandr Krasouski	Belarus
	1	Bálint Móricz	Hungary
	1	Luka Janezic	Slovenia
	1	Thomas Jordier	France
	1	Mateo Ruzic	Croatia
	1	Danil Peremetov	Russia
	1	Rafal Smolen	Poland
	1	Ben Snaith	Great Britain
	2	Milos Raovic	Serbia
	2	Sondre Nyvold Lid	Norway
	2	Bastien Mandrou	France
	2	Pavel Ivashko	Russia
	2	Oleksiy Pozdnyakov	Ukraine
	2	Patryk Dobek	Poland
	2	Dennis Forsman	Sweden
	2	Marc Koch	Germany

Wind: