An apparatus (100, 200, 201, 202, 300, 301, 400, 402, 500, 501, 502, 600, 601, 602, 700, 800, 800-1, 800-2, 900, 901, 902, 903, 904, 905, 906, 1100, 1101) for measuring bioelectrical signals, the apparatus comprising: at least one sensor electrode (151, 151-1/2/3/4, 251, 251-1/2/3, 921, 921-1, 922, 922-1, 923, 923-1, 2010) a sensor support (120, 120-1/2/3/4/5/6/7/8, 175, 330, 550, 855, 872, 2100) configured to support the sensor electrode to maintain the contact between the sensor electrode and a body part; a main body (110, 210, 410, 411, 610, 710, 810, 910) connected to the sensor support and being wearable on a living body; an electrode supporter (153, 252, 2030) that is configured to support the sensor electrode; wherein each sensor electrode has a funnel shape having a combination of a tapering portion (151a, 151-1a/2a/3a/4a, 251-1a, 251-2a, 251-3a, 2010a) and a corresponding protruding portion (151b, 151-1b/2b/3b/4b, 251-2b, 2010b) configured to contact said body part and wherein the protruding portion is configured to bend when a force is applied to the sensor electrode in the direction of the body part; wherein the tapering portion is arranged between the electrode supporter (153, 252, 2030) and the protruding portion (151b, 151-1b/2b/3b/4b, 251-2b, 2010b) and wherein the tapering portion is configured to support the protruding portion; wherein the tapering portion narrows toward a tapered end that is directed away from the electrode supporter and the protruding portion extends from said tapered end; and wherein the protruding portion comprises a flexible material and has a flexibility greater than a flexibility of the tapering portion, characterised in that only the protruding portion of the sensor electrode is configured to bend when the electrode is in contact with the body part and when a force is applied to the sensor electrode in the direction of the body part, wherein an outer circumferential surface of the protruding portion is configured to contact the body part. at least one sensor electrode (151, 151-1/2/3/4, 251, 251-1/2/3, 921, 921-1, 922, 922-1, 923, 923-1, 2010) a sensor support (120, 120-1/2/3/4/5/6/7/8, 175, 330, 550, 855, 872, 2100) configured to support the sensor electrode to maintain the contact between the sensor electrode and a body part; a main body (110, 210, 410, 411, 610, 710, 810, 910) connected to the sensor support and being wearable on a living body; an electrode supporter (153, 252, 2030) that is configured to support the sensor electrode; wherein each sensor electrode has a funnel shape having a combination of a tapering portion (151a, 151-1a/2a/3a/4a, 251-1a, 251-2a, 251-3a, 2010a) and a corresponding protruding portion (151b, 151-1b/2b/3b/4b, 251-2b, 2010b) configured to contact said body part and wherein the protruding portion is configured to bend when a force is applied to the sensor electrode in the direction of the body part; wherein the tapering portion is arranged between the electrode supporter (153, 252, 2030) and the protruding portion (151b, 151-1b/2b/3b/4b, 251-2b, 2010b) and wherein the tapering portion is configured to support the protruding portion; wherein the tapering portion narrows toward a tapered end that is directed away from the electrode supporter and the protruding portion extends from said tapered end; and wherein the protruding portion comprises a flexible material and has a flexibility greater than a flexibility of the tapering portion, characterised in that only the protruding portion of the sensor electrode is configured to bend when the electrode is in contact with the body part and when a force is applied to the sensor electrode in the direction of the body part, wherein an outer circumferential surface of the protruding portion is configured to contact the body part.