A biological sensor that is to be affixed to a living body and is for acquiring a biological signal, the biological sensor comprising: a cover member; and a porous substrate having a porous structure, the porous substrate being disposed on the cover member on a side of the living body, wherein a sticking layer, including the porous substrate and a first adhesive layer that is disposed on the porous substrate on a side of the living body, exhibits a shear stress of from 5×10 4 N/m 2 to 65×10 4 N/m 2 when the sticking layer is deformed in a direction perpendicular to a thickness direction of the sticking layer by 5% to 15% of a length of the sticking layer, wherein the thickness of the porous substrate is within a range from 0.5 mm to 1.5 mm and the thickness of the first adhesive layer is within a range from 10 um to 300 um, wherein a moisture permeability of the sticking layer is within a range from 65 g/m 2 ·day to 4000 g/m 2 ·day, and wherein the biological sensor further comprises: an electrode affixed to the first adhesive layer; a sensor body that is connected to the electrode and acquires biological information; and a second substrate on which the sensor body is mounted, wherein the cover member includes a concave portion formed in a recessed shape on a side of the living body, wherein the porous substrate has a through hole at a position facing the concave portion, and wherein the concave portion and the through hole form a storage space for storing the sensor body. a cover member; and a porous substrate having a porous structure, the porous substrate being disposed on the cover member on a side of the living body, wherein a sticking layer, including the porous substrate and a first adhesive layer that is disposed on the porous substrate on a side of the living body, exhibits a shear stress of from 5×10 4 N/m 2 to 65×10 4 N/m 2 when the sticking layer is deformed in a direction perpendicular to a thickness direction of the sticking layer by 5% to 15% of a length of the sticking layer, wherein the thickness of the porous substrate is within a range from 0.5 mm to 1.5 mm and the thickness of the first adhesive layer is within a range from 10 um to 300 um, wherein a moisture permeability of the sticking layer is within a range from 65 g/m 2 ·day to 4000 g/m 2 ·day, and wherein the biological sensor further comprises: an electrode affixed to the first adhesive layer; a sensor body that is connected to the electrode and acquires biological information; and a second substrate on which the sensor body is mounted, wherein the cover member includes a concave portion formed in a recessed shape on a side of the living body, wherein the porous substrate has a through hole at a position facing the concave portion, and wherein the concave portion and the through hole form a storage space for storing the sensor body. an electrode affixed to the first adhesive layer; a sensor body that is connected to the electrode and acquires biological information; and a second substrate on which the sensor body is mounted, wherein the cover member includes a concave portion formed in a recessed shape on a side of the living body, wherein the porous substrate has a through hole at a position facing the concave portion, and wherein the concave portion and the through hole form a storage space for storing the sensor body.