A thermoplastic elastomer composition comprising: a thermoplastic elastomer obtained by reacting: an ethylene copolymer comprising 50% by weight to 95% by weight of monomer units derived from ethylene and 5% by weight to 50% by weight of monomer units derived from at least one selected from the group consisting of propylene and α-olefins having 4 to 10 carbon atoms (component) where the total amount of the monomer units derived from ethylene and the monomer units derived from at least one selected from the group consisting of propylene and α-olefins having 4 to 10 carbon atoms is taken as 100% by weight, a propylene polymer comprising monomer units derived from propylene, wherein the content of the monomer units derived from propylene exceeds 50% by weight (component), where the whole amount of the component is taken as 100% by weight, and a crosslinking agent, wherein the weight ratio of the component before reacting with the crosslinking agent to the component before reacting with the crosslinking agent (the weight of the component /the weight of the component) is from 0.5 to 20, and further comprising: 35 parts by weight to 200 parts by weight of a phosphoric acid salt compound (component), 0.1 parts by weight to 40 parts by weight of a metal oxide comprising a metal having an atomic weight of 22 to 64 or a metal hydroxide comprising a metal having an atomic weight of 22 to 64 (component), and 0.1 parts by weight to 40 parts by weight of a polyhydric compound (component), the contents of the component, the component, and the component each being based on 100 parts by weight in total of the component before reacting with the crosslinking agent and the component before reacting with the crosslinking agent, wherein the weight ratio of the component to the component (the weight of the component /the weight of the component) is from 4 to 200. a thermoplastic elastomer obtained by reacting: an ethylene copolymer comprising 50% by weight to 95% by weight of monomer units derived from ethylene and 5% by weight to 50% by weight of monomer units derived from at least one selected from the group consisting of propylene and α-olefins having 4 to 10 carbon atoms (component) where the total amount of the monomer units derived from ethylene and the monomer units derived from at least one selected from the group consisting of propylene and α-olefins having 4 to 10 carbon atoms is taken as 100% by weight, a propylene polymer comprising monomer units derived from propylene, wherein the content of the monomer units derived from propylene exceeds 50% by weight (component), where the whole amount of the component is taken as 100% by weight, and a crosslinking agent, wherein the weight ratio of the component before reacting with the crosslinking agent to the component before reacting with the crosslinking agent (the weight of the component /the weight of the component) is from 0.5 to 20, and further comprising: an ethylene copolymer comprising 50% by weight to 95% by weight of monomer units derived from ethylene and 5% by weight to 50% by weight of monomer units derived from at least one selected from the group consisting of propylene and α-olefins having 4 to 10 carbon atoms (component) where the total amount of the monomer units derived from ethylene and the monomer units derived from at least one selected from the group consisting of propylene and α-olefins having 4 to 10 carbon atoms is taken as 100% by weight, a propylene polymer comprising monomer units derived from propylene, wherein the content of the monomer units derived from propylene exceeds 50% by weight (component), where the whole amount of the component is taken as 100% by weight, and a crosslinking agent, wherein the weight ratio of the component before reacting with the crosslinking agent to the component before reacting with the crosslinking agent (the weight of the component /the weight of the component) is from 0.5 to 20, and further comprising: 35 parts by weight to 200 parts by weight of a phosphoric acid salt compound (component), 0.1 parts by weight to 40 parts by weight of a metal oxide comprising a metal having an atomic weight of 22 to 64 or a metal hydroxide comprising a metal having an atomic weight of 22 to 64 (component), and 0.1 parts by weight to 40 parts by weight of a polyhydric compound (component), the contents of the component, the component, and the component each being based on 100 parts by weight in total of the component before reacting with the crosslinking agent and the component before reacting with the crosslinking agent, wherein the weight ratio of the component to the component (the weight of the component /the weight of the component) is from 4 to 200.