An engine having a chain chamber, comprising: a crankshaft; a camshaft; a first sprocket attached to said crankshaft; a second sprocket attached to said camshaft; a crankcase that stores said first sprocket; a cylinder body attached to said crankcase; a cylinder head attached to said cylinder body to store said second sprocket; a chain wrapped around said first and second sprockets (108, 146); and a tension providing member that provides said chain with tension, said crankcase, said cylinder body, and said cylinder head forming said chain chamber that stores said chain and said tension providing member, said tension providing member comprising: a plate spring member; and a contact member that supports said plate spring member and contacts said chain in said chain chamber, said engine further comprising: a support shaft inserted through a support hole formed at said contact member to support said tension providing member in a swingable manner, characterized in that said engine further comprises: a support part that supports said tension providing member by contacting a supported part formed at said contact member, said support part supporting said supported part so that said supported part can slide in said chain chamber when said tension providing member swings around said support shaft, said support part comprises: a support surface contacted by said supported part; and a pair of opposite walls (218c, 218d) provided to have said tension providing member therebetween, the support surface extending between the opposite walls (218c, 218d) and said support surface and said pair of opposite walls (218c, 218d) are provided integrally, and said support part is integrally formed with one of said cylinder body and said cylinder head. a crankshaft; a camshaft; a first sprocket attached to said crankshaft; a second sprocket attached to said camshaft; a crankcase that stores said first sprocket; a cylinder body attached to said crankcase; a cylinder head attached to said cylinder body to store said second sprocket; a chain wrapped around said first and second sprockets (108, 146); and a tension providing member that provides said chain with tension, said crankcase, said cylinder body, and said cylinder head forming said chain chamber that stores said chain and said tension providing member, said tension providing member comprising: a plate spring member; and a contact member that supports said plate spring member and contacts said chain in said chain chamber, a plate spring member; and a contact member that supports said plate spring member and contacts said chain in said chain chamber, said engine further comprising: a support shaft inserted through a support hole formed at said contact member to support said tension providing member in a swingable manner, a support shaft inserted through a support hole formed at said contact member to support said tension providing member in a swingable manner, a support part that supports said tension providing member by contacting a supported part formed at said contact member, said support part supporting said supported part so that said supported part can slide in said chain chamber when said tension providing member swings around said support shaft, said support part comprises: a support surface contacted by said supported part; and a pair of opposite walls (218c, 218d) provided to have said tension providing member therebetween, the support surface extending between the opposite walls (218c, 218d) and said support surface and said pair of opposite walls (218c, 218d) are provided integrally, and said support part is integrally formed with one of said cylinder body and said cylinder head. a support surface contacted by said supported part; and a pair of opposite walls (218c, 218d) provided to have said tension providing member therebetween, the support surface extending between the opposite walls (218c, 218d) and said support surface and said pair of opposite walls (218c, 218d) are provided integrally, and said support part is integrally formed with one of said cylinder body and said cylinder head.