An MEMS sensor comprising: a first substrate (1; 101); a second substrate (2; 102); a movable electrode portion and a fixed electrode portion (11, 13) which are arranged between the first substrate and the second substrate, wherein: conductive supporting portions (12, 14, 17, 19; 116) of the movable electrode portion and the fixed electrode portion (11, 13) are, respectively, fixedly secured to a surface of the first substrate (1; 103) via a first insulating layer (3a, 3b, 3c; 103); a second insulating layer (30; 130), a lead layer (34, 35), and connection electrode portions (31, 32) that are electrically connected to the lead layer (34, 35; 130) to be individually connected to the conductive supporting portions (12, 14, 17, 19; 116) are provided on a surface of the second substrate (2; 102); a metallic connection layer (41, 42) is formed on the surface of one of the respective conductive supporting portions (12, 14, 17, 19); one of the respective connection electrode portions (31, 32) and the metallic connection layer (41, 42) are bonded together by eutectic bonding or diffusion bonding forming a bonding layer having a thickness of 4 μm or smaller; wherein a first portion of the second insulating layer (30; 130) is provided between the lead layer (34, 35) and the second substrate (2; 102) and a second portion of the second insulating layer (30; 130) is provided on a surface of the lead layer (34, 35) to bury the lead layer (34, 35) into the second insulating layer (30; 130); a concave portion is formed on the second insulating layer (30; 130) so as to oppose the movable electrode portion; and a continuous or discontinuous groove (51, 52) is formed in the conductive supporting portions (12, 14, 17, 19) so as to surround the bonding layer between the connection electrode portions (31, 32) and the metallic connection layer (41, 42). a first substrate (1; 101); a second substrate (2; 102); a movable electrode portion and a fixed electrode portion (11, 13) which are arranged between the first substrate and the second substrate, wherein: conductive supporting portions (12, 14, 17, 19; 116) of the movable electrode portion and the fixed electrode portion (11, 13) are, respectively, fixedly secured to a surface of the first substrate (1; 103) via a first insulating layer (3a, 3b, 3c; 103); a second insulating layer (30; 130), a lead layer (34, 35), and connection electrode portions (31, 32) that are electrically connected to the lead layer (34, 35; 130) to be individually connected to the conductive supporting portions (12, 14, 17, 19; 116) are provided on a surface of the second substrate (2; 102); a metallic connection layer (41, 42) is formed on the surface of one of the respective conductive supporting portions (12, 14, 17, 19); one of the respective connection electrode portions (31, 32) and the metallic connection layer (41, 42) are bonded together by eutectic bonding or diffusion bonding forming a bonding layer having a thickness of 4 μm or smaller; wherein a first portion of the second insulating layer (30; 130) is provided between the lead layer (34, 35) and the second substrate (2; 102) and a second portion of the second insulating layer (30; 130) is provided on a surface of the lead layer (34, 35) to bury the lead layer (34, 35) into the second insulating layer (30; 130); a concave portion is formed on the second insulating layer (30; 130) so as to oppose the movable electrode portion; and a continuous or discontinuous groove (51, 52) is formed in the conductive supporting portions (12, 14, 17, 19) so as to surround the bonding layer between the connection electrode portions (31, 32) and the metallic connection layer (41, 42). conductive supporting portions (12, 14, 17, 19; 116) of the movable electrode portion and the fixed electrode portion (11, 13) are, respectively, fixedly secured to a surface of the first substrate (1; 103) via a first insulating layer (3a, 3b, 3c; 103); a second insulating layer (30; 130), a lead layer (34, 35), and connection electrode portions (31, 32) that are electrically connected to the lead layer (34, 35; 130) to be individually connected to the conductive supporting portions (12, 14, 17, 19; 116) are provided on a surface of the second substrate (2; 102); a metallic connection layer (41, 42) is formed on the surface of one of the respective conductive supporting portions (12, 14, 17, 19); one of the respective connection electrode portions (31, 32) and the metallic connection layer (41, 42) are bonded together by eutectic bonding or diffusion bonding forming a bonding layer having a thickness of 4 μm or smaller; wherein a first portion of the second insulating layer (30; 130) is provided between the lead layer (34, 35) and the second substrate (2; 102) and a second portion of the second insulating layer (30; 130) is provided on a surface of the lead layer (34, 35) to bury the lead layer (34, 35) into the second insulating layer (30; 130); a concave portion is formed on the second insulating layer (30; 130) so as to oppose the movable electrode portion; and a continuous or discontinuous groove (51, 52) is formed in the conductive supporting portions (12, 14, 17, 19) so as to surround the bonding layer between the connection electrode portions (31, 32) and the metallic connection layer (41, 42).