A method for transmitting a signal by using resource units each having a plurality of subcarriers in a wireless local area network, WLAN, system, the method comprising: configuring a Physical Protocol Data Unit, PPDU, by using at least one resource unit, RU, allocated for a data field of a receiving station, wherein each RU is one of a first type RU, a second type RU including a larger number of subcarriers than a first type RU and a third type RU including a larger number of subcarriers than a second type RU; and transmitting the PPDU to the receiving station through a predetermined band (480; 580; 680; 780; 880; 980; 1080; 1180; 1280; 1380; 1480; 1580), the predetermined band including first to fifth frequency bands each being contiguous with one another, a left guard band (460; 560; 660; 760; 860; 960; 1060; 1160; 1260; 1360; 1460; 1560) being contiguous with the first frequency band (410; 510; 610; 710; 810; 910; 1010; 1110; 1210; 1310; 1410; 1510), and a right guard band (470; 570; 670; 770; 870; 970; 1070; 1170; 1270; 1370; 1470; 1570) being contiguous with the fifth frequency band (450; 550; 650; 750; 850; 950; 1050; 1150; 1250; 1350; 1450; 1550), wherein, in case a first type or second type RU is allocated to the first frequency band (410; 510; 610; 710; 910), a leftmost subcarrier (415; 515; 615; 715; 915) of the first frequency band is a null subcarrier, wherein, in case a first type or second type RU is allocated to the second frequency band (420; 620; 720; 820; 1020; 1120; 1220; 1320; 1420; 1520), a leftmost subcarrier (425; 625; 725; 825; 1025; 1121, 1122; 1221, 1222; 1325; 1421; 1525) of the second frequency band is a null subcarrier, wherein, in case a third type RU is allocated to the first and second frequency bands, the first and second frequency bands include no null subcarrier, wherein, in case a first type or second type RU is allocated to the fourth frequency band (440; 640; 740; 840; 1040; 1140; 1240; 1340; 1440; 1540), a rightmost subcarrier (445; 645; 745; 845; 1045; 1141, 1142; 1241, 1242; 1345; 1442; 1545) of the fourth frequency band is a null subcarrier, wherein, in case a first type or second type RU is allocated to the fifth frequency band (450; 550; 650; 750; 950), a rightmost subcarrier (455; 555; 655; 755; 955) of the fifth frequency band is a null subcarrier, wherein, in case a third type RU is allocated to the fourth and fifth frequency bands, the fourth and fifth frequency bands include no null subcarrier. configuring a Physical Protocol Data Unit, PPDU, by using at least one resource unit, RU, allocated for a data field of a receiving station, wherein each RU is one of a first type RU, a second type RU including a larger number of subcarriers than a first type RU and a third type RU including a larger number of subcarriers than a second type RU; and transmitting the PPDU to the receiving station through a predetermined band (480; 580; 680; 780; 880; 980; 1080; 1180; 1280; 1380; 1480; 1580), the predetermined band including first to fifth frequency bands each being contiguous with one another, a left guard band (460; 560; 660; 760; 860; 960; 1060; 1160; 1260; 1360; 1460; 1560) being contiguous with the first frequency band (410; 510; 610; 710; 810; 910; 1010; 1110; 1210; 1310; 1410; 1510), and a right guard band (470; 570; 670; 770; 870; 970; 1070; 1170; 1270; 1370; 1470; 1570) being contiguous with the fifth frequency band (450; 550; 650; 750; 850; 950; 1050; 1150; 1250; 1350; 1450; 1550), wherein, in case a first type or second type RU is allocated to the first frequency band (410; 510; 610; 710; 910), a leftmost subcarrier (415; 515; 615; 715; 915) of the first frequency band is a null subcarrier, wherein, in case a first type or second type RU is allocated to the second frequency band (420; 620; 720; 820; 1020; 1120; 1220; 1320; 1420; 1520), a leftmost subcarrier (425; 625; 725; 825; 1025; 1121, 1122; 1221, 1222; 1325; 1421; 1525) of the second frequency band is a null subcarrier, wherein, in case a third type RU is allocated to the first and second frequency bands, the first and second frequency bands include no null subcarrier, wherein, in case a first type or second type RU is allocated to the fourth frequency band (440; 640; 740; 840; 1040; 1140; 1240; 1340; 1440; 1540), a rightmost subcarrier (445; 645; 745; 845; 1045; 1141, 1142; 1241, 1242; 1345; 1442; 1545) of the fourth frequency band is a null subcarrier, wherein, in case a first type or second type RU is allocated to the fifth frequency band (450; 550; 650; 750; 950), a rightmost subcarrier (455; 555; 655; 755; 955) of the fifth frequency band is a null subcarrier, wherein, in case a third type RU is allocated to the fourth and fifth frequency bands, the fourth and fifth frequency bands include no null subcarrier.