A collision detection device for a vehicle, comprising: a bumper absorber that is placed on a vehicle front side of a bumper reinforcement in a bumper of the vehicle; a detection tube member that is attached to a groove portion formed on a rear surface of the bumper absorber along a vehicle width direction and that includes therein a hollow part; the groove portion of the bumper absorber includes a straight part extending in a vehicle horizontal direction, and a curved part non-parallel to the straight part; a pressure sensor that detects a pressure in the hollow part of the detection - tube member; and a collision detection part that detects a collision of an object with the bumper based on a result of the pressure detection by the pressure sensor, wherein: the bumper absorber includes general parts and holding parts (21, 22a, 23, 24) alternately in a lengthwise direction of the groove portion; in each of the general parts, a predetermined clearance is formed; characterized in that the predetermined clearance is formed between an inner wall surface of the groove portion on at least one side of vehicle up and down sides, and the detection tube member; each of the holding parts (21, 22a, 23, 24) is in contact with a surface of the detection tube member on the vehicle up and front sides, or the vehicle down and front sides to hold the detection tube member; the curved part is curved in a vehicle up-down direction; a holding part ratio, which is a ratio of a part of the detection tube member held by the holding parts (21, 22a, 23, 24) to a unit length of the detection tube member, is set to be smaller than a predetermined value; and the holding part ratio at the curved part is set to be higher than the holding part ratio at the straight part. a bumper absorber that is placed on a vehicle front side of a bumper reinforcement in a bumper of the vehicle; a detection tube member that is attached to a groove portion formed on a rear surface of the bumper absorber along a vehicle width direction and that includes therein a hollow part; the groove portion of the bumper absorber includes a straight part extending in a vehicle horizontal direction, and a curved part non-parallel to the straight part; a pressure sensor that detects a pressure in the hollow part of the detection - tube member; and a collision detection part that detects a collision of an object with the bumper based on a result of the pressure detection by the pressure sensor, wherein: the bumper absorber includes general parts and holding parts (21, 22a, 23, 24) alternately in a lengthwise direction of the groove portion; in each of the general parts, a predetermined clearance is formed; characterized in that the predetermined clearance is formed between an inner wall surface of the groove portion on at least one side of vehicle up and down sides, and the detection tube member; each of the holding parts (21, 22a, 23, 24) is in contact with a surface of the detection tube member on the vehicle up and front sides, or the vehicle down and front sides to hold the detection tube member; the curved part is curved in a vehicle up-down direction; a holding part ratio, which is a ratio of a part of the detection tube member held by the holding parts (21, 22a, 23, 24) to a unit length of the detection tube member, is set to be smaller than a predetermined value; and the holding part ratio at the curved part is set to be higher than the holding part ratio at the straight part. the bumper absorber includes general parts and holding parts (21, 22a, 23, 24) alternately in a lengthwise direction of the groove portion; in each of the general parts, a predetermined clearance is formed; characterized in that the predetermined clearance is formed between an inner wall surface of the groove portion on at least one side of vehicle up and down sides, and the detection tube member; each of the holding parts (21, 22a, 23, 24) is in contact with a surface of the detection tube member on the vehicle up and front sides, or the vehicle down and front sides to hold the detection tube member; the curved part is curved in a vehicle up-down direction; a holding part ratio, which is a ratio of a part of the detection tube member held by the holding parts (21, 22a, 23, 24) to a unit length of the detection tube member, is set to be smaller than a predetermined value; and the holding part ratio at the curved part is set to be higher than the holding part ratio at the straight part.