| POS | Rank | Heat | BIB | ATHLETE | COUNTRY | RESULTS | ms* |
|---|---|---|---|---|---|---|---|
| 1 | 1 | 1 | POL | Poland U20 |
POL |
38.93 Q AU20R | |
| 2 | 2 | 1 | JAM | Jamaica U20 |
JAM |
39.00 Q SB | |
| 3 | 1 | 2 | RSA | South Africa U20 |
RSA |
39.33 Q AU20R | .324 |
| 4 | 3 | 1 | NGR | Nigeria U20 |
NGR |
39.33 Q AU20R | .325 |
| 5 | 2 | 2 | ITA | Italy U20 |
ITA |
39.56 Q SB | |
| 6 | 4 | 1 | COL | Colombia U20 |
COL |
40.04 q NU20R | |
| 7 | 3 | 2 | GRE | Greece U20 |
GRE |
40.13 Q NU20R | |
| 8 | 4 | 2 | KSA | Saudi Arabia U20 |
KSA |
40.40 q SB | |
| 9 | 5 | 1 | SWZ | Eswatini U20 |
SWZ |
41.34 NU20R | |
| 10 | 6 | 1 | FIN | Finland U20 |
FIN |
50.88 | |
| 2 | BOT | Botswana U20 |
BOT |
DQ | |||
| 2 | ECU | Ecuador U20 |
ECU |
DQ | |||
| 2 | BRA | Brazil U20 |
BRA |
DQ | |||
| 1 | QAT | Qatar U20 |
QAT |
DQ |
ms - Milliseconds - shown when two or more competitors finish with the same time down to hundredths of a second